p38 Mitogen activated protein kinase (MAPK): a new therapeutic target for reducing the risk of adverse pregnancy outcomes

The Role of the NLRP3 Inflammasome in the Molecular and Biochemical Mechanisms of Cervical Ripening: A Comprehensive Review

The uterine cervix is one of the key factors involved in ensuring a proper track of gestation and labor. At the end of the gestational period, the cervix undergoes extensive changes, which can be summarized as a transformation from a non-favorable cervix to one that is soft and prone to dilation. During a process called cervical ripening, fundamental remodeling of the cervical extracellular matrix (ECM) occurs. The cervical ripening process is a derivative of many interlocking and mutually driving biochemical and molecular pathways under the strict control of mediators such as inflammatory cytokines, nitric oxide, prostaglandins, and reactive oxygen species. A thorough understanding of all these pathways and learning about possible triggering factors will allow us to develop new, better treatment algorithms and therapeutic goals that could protect women from both dysfunctional childbirth and premature birth. This review aims to present the possible role of the NLRP3 inflammasome in the cervical ripening process, emphasizing possible mechanisms of action and regulatory factors.

Chromogranin A: An Endocrine Factor of Pregnancy

Pregnancy is a state of physiological and hormonal changes. One of the endocrine factors involved in these processes is chromogranin A, an acidic protein produced, among others, by the placenta. Although it has been previously linked to pregnancy, no existing articles have ever managed to clarify the role of this protein regarding this subject. Therefore, the aim of the present study is to gather knowledge of chromogranin A's function with reference to gestation and parturition, clarify elusive information, and, most importantly, to formulate hypotheses for the future studies to verify.

Cellular senescence in normal and adverse pregnancy

Cellular senescence (CS) is defined as a state of terminal proliferation arrest accompanied by morphological alterations, pro-inflammatory phenotype, and metabolic changes. In recent years, the implications of senescence in numerous physiological and pathological conditions such as development, tissue repair, aging, or cancer have been evident. Some inductors of senescence are tissue repair pathways, telomere shortening, DNA damage, degenerative disorders, and wound healing. Lately, it has been demonstrated that CS plays a decisive role in the development and progression of healthy pregnancy and labor. Premature maternal-fetal tissues senescence (placenta, choriamniotic membranes, and endothelium) is implicated in many adverse pregnancy outcomes, including fetal growth restriction, preeclampsia, preterm birth, and intrauterine fetal death. Here we discuss cellular senescence and its association with normal pregnancy development and adverse pregnancy outcomes. Current evidence allows us to establish the relevance of CS in processes associated with the appropriate development of placentation, the progression of pregnancy, and the onset of labor; likewise, it allows us to understand the undeniable participation of CS deregulation in pathological processes associated with pregnancy.

The Potential Mechanism of Zishen Yutai Pills against Threatened Abortion: An Approach Involving Network Pharmacology and Experimental Evidence

Threatened abortion (TA) is the most common complication in early pregnancy and is caused by anxiety and depressive symptoms. The Zishen Yutai Pill (ZYP) is a traditional herbal formula that is commonly used to treat TA. However, the pharmacological mechanisms underlying the effect of ZYP have yet to be elucidated. To disclose the mechanism of ZYP in the treatment of TA, first, we identified the chemical constituents of ZYP from multiple databases and then predicted the potential targets of TA by applying the GeneCards database. A protein-protein interaction (PPI) network was then constructed to allow the screening of hub targets. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGGs) enrichment analyses were also performed and the Database for Annotation Visualization and Integrated Discovery server was used to identify critical biological processes and signaling pathways. Cytoscape software was used to construct a Compound-Target-Pathway. Furthermore, we analyzed ZYP by UPLC-Q-TOF/MS, then the RU486-induced TA rat model was established, and the reliability of the network pharmacology prediction results was verified. Finally, the mechanisms responsible for the action of ZYP on TA were revealed by qRT-PCR and molecular docking. Database screening identified a total of 161 active compounds in ZYP and 324 TA-related targets. And, we identified 42 compounds from ZYP by UPLC-Q-TOF/MS. Inflammation and apoptosis were identified as the main biological processes. GO and KEGG analyses identified that the MAPK and PI3K/Akt pathways were the key functional pathways that respond to ZYP. The results showed that ZYP treatment significantly increased maternal weight, significantly increased the levels of estradiol and progesterone, and attenuated histopathological changes in a rat model of TA. Data indicated that ZYP treatment improved pregnancy outcomes in the rat model of TA. QRT-PCR data showed that ZYP reduced inflammation and apoptosis by regulating the MAPK and PI3K/Akt pathways. In addition, molecule docking results identified a range of key compounds, including Pik3a, Mapk14, Mapk1, Mapk3, Mapk8 Tnf, Il6, and Cas8. In summary, we performed network pharmacological analysis and experimental validation and identified that ZYP exerts an effect on TA by regulating the MAPK and PI3K/Akt pathways and by inhibiting the expression levels of proinflammatory cytokines and genes related to apoptosis.

Stress signaler p38 mitogen-activated kinase activation: a cause for concern?

Oxidative stress (OS) induced activation of p38 mitogen-activated kinase (MAPK) and cell fate from p38 signaling was tested using the human fetal membrane's amnion epithelial cells (AEC). We created p38 KO AEC using the CRISPR/Cas9 approach and tested cell fate in response to OS on an AEC-free fetal membrane extracellular matrix (ECM). Screening using image CyTOF indicated OS causing epithelial-mesenchymal transition (EMT). Further testing revealed p38 deficiency prevented AEC senescence, EMT, cell migration, and inflammation. To functionally validate in vitro findings, fetal membrane-specific conditional KO (cKO) mice were developed by injecting Cre-recombinase encoded exosomes intra-amniotically into p38αloxP/loxP mice. Amnion membranes from p38 cKO mice had reduced senescence, EMT, and increased anti-inflammatory IL-10 compared with WT animals. Our study suggested that overwhelming activation of p38 in response to OS inducing risk exposures can have an adverse impact on cells, cause cell invasion, inflammation, and ECM degradation detrimental to tissue homeostasis.

Dinitramine induces implantation failure by cell cycle arrest and mitochondrial dysfunction in porcine trophectoderm and luminal epithelial cells

The herbicide market is growing rapidly, as weed control is a significant challenge in agriculture. Many studies have reported the toxicity of herbicides to non-target organisms. Dinitramine is a dinitroaniline herbicide that is particularly toxic to aquatic organisms. However, little is known about the effects of dinitramine on the female reproductive system. Therefore, in the present study, we utilized porcine trophectoderm (pTr) cells and porcine endometrial luminal epithelial (pLE) cells to verify the reproductive toxicity of dinitramine. Dinitramine reduced the viability of both cell types, by triggering cell cycle arrest, especially at the sub-G1 phase, and increasing apoptosis, inhibiting DNA replication. Dinitramine disrupted intracellular calcium homeostasis and induced oxidative stress by producing reactive oxygen species, leading to the loss of mitochondrial membrane potential and alteration of mitochondrial respiration. Mitogen-activated protein kinase pathways were altered, and migration decreased in pTr and pLE cells after dinitramine treatment; the expression of pregnancy-related genes in these cells was decreased. Thus, dinitramine reduced the viability and migratory capacity of both cell types, and this could interrupt the early stages of pregnancy.

Leveraging bioengineering to assess cellular functions and communication within human fetal membranes

The fetal membranes enclose the growing fetus and amniotic fluid. Preterm prelabor rupture of fetal membranes is a leading cause of preterm birth. Fetal membranes are composed of many different cell types, both structural and immune. These cells must coordinate functions for tensile strength and membrane integrity to contain the growing fetus and amniotic fluid. They must also balance immune responses to pathogens with maintaining maternal-fetal tolerance. Perturbation of this equilibrium can lead to preterm premature rupture of membranes without labor. In this review, we describe the formation of the fetal membranes to orient the reader, discuss some of the common forms of communication between the cell types of the fetal membranes, and delve into the methods used to tease apart this paracrine signaling within the membranes, including emerging technologies such as organ-on-chip models of membrane immunobiology.

Computational Screening of the Natural Product Osthole and Its Derivates for Anti-Inflammatory Activity

Osthole (OS) is a natural coumarin with a long history of medicinal use in a variety of diseases, such as itch and menstrual disorders. In recent years, OS has been shown to treat inflammation and reduce the expression and activity of NF-κB, although its mechanism of action is still unclear. Overexpression of inflammatory cytokines can have many negative effects in the body, including inducing preterm labor; thus, the modulation of inflammation by OS and its derivatives may be able to delay preterm birth, increasing neonatal survival rates. The objectives of this study were to screen and identify the derivatives of OS with the highest potential for binding capacity to inflammatory mediators NF-κB, TNF-α, and ERK1, and to measure the drug-like properties of these compounds. GLIDE docking in Schrodinger Maestro software was used to calculate docking scores for a variety of semi-synthetic OS derivatives against three proteins involved in inflammation: NF-κB, TNF-α, and ERK1. Schrodinger Qikprop was also used to measure the pharmaceutically relevant properties of the compounds. The protonated demethoxy osthole 1 showed the highest docking of all the proteins tested, while the deprotonated demethoxy osthole 2 consistently had the lowest scores, denoting the importance of pH in the binding activity of this derivative. The lowest docking was at NF-κB, suggesting that this is less likely to be the primary target of OS. All of the screened derivatives showed high drug potential, based on their Qikprop properties. OS and its derivatives showed potential to bind to multiple proteins that regulate the inflammatory response and are prospective candidates for delaying preterm birth.

Transcriptome Comparison of Chorion-Attached and Non-chorion-attached Endometrium in Mid-gestation of Rabbit

Background

The chorion from the placenta is directly attached to the endometrium (CA) after embryo implantation while some parts of the endometrium are not chorion-attached (NCA). The differences in gene expression between the CA and NCA endometrium mid-gestation are unknown. Our objective was to compare the gene expression profiles of the CA and NCA endometrium of rabbit, to identify the differentially expressed genes (DEGs), and correlate the differences with the physiological state of the endometrium at mid-gestation of rabbit.

Methods

We used transcriptome sequencing to reveal the differences in gene expression between CA and NCA endometrium (n = 3), and then determined the concentration of inflammatory cytokines in CA and NCA tissue and serum by ELISA.

Results

Six Hundred and Forty-Six DEGs were identified between the CA and NCA endometrium [p < 0.05, |log2 (fold change) |≥ 2], The expression levels of 590 DEGs were higher in the NCA endometrium than in the CA endometrium, while the expression level of only 56 DEGs were higher in CA than in NCA. The DEGs were enriched in gene ontology (GO) terms and pathways related to immune regulation and cellular adhesions. Six hub-genes related to inflammatory mediator regulation of transient receptor potential (TRP) channels and chemokine signaling pathways had a lower expression level in the CA endometrium compared to the NCA endometrium, and the expression levels of genes related to focal adhesion and extracellular matrix (ECM)-receptors were significantly higher in NCA endometrium than in CA endometrium. The level of pro-inflammatory cytokines accumulated in the CA endometrium, and high abundance of integrin-β and THBS1 were localized in the luminal epithelium of the NCA endometrium, but not in the CA endometrium.

Conclusions

Our study reveals differences in gene expression between the CA and NCA endometrium at mid-gestation of rabbit, and suggests implications for endometrial physiological function. The CA endometrium showed relative low-level gene expression compared to the NCA endometrium, while the NCA endometrium performed physiological functions related to focal adhesion and ECM-receptor interaction.

Actions of Bisphenol A on Different Feto-Maternal Compartments Contributing to Preterm Birth

Preterm birth remains to be one of the most prevalent obstetric complications worldwide. Since there are multiple etiological factors associated with this disease process, an integrative literature search in PubMed and Scopus databases on possible mechanism of action and effect of bisphenols on exposure on human or animal placental samples in preterm birth was conducted. From 2332 articles on initial literature search, 63 studies were included for full data extraction. Altogether, several pathways were shown to be possibly affected by bisphenols, leading to dysregulations in structural and endocrine foundation in the placenta, potential induction of senescence and failure of decidualization in the decidua, and possible propagation of inflammation in the fetal membranes. Combined, these actions may eventually counteract bisphenol-induced relaxation of the myometrium and promote contractility alongside fetal membrane weakening. In totality, these individual impairments in gestation-critical processes may lead to failure of maintenance of pregnancy, and thus effecting preterm birth.

MAPK /ERK signaling pathway: A potential target for the treatment of intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is a chronic skeletal muscle degenerative disease, which is considered the main cause of low back pain. It seriously affects the quality of life of patients and consequently brings a heavy economic burden to their families and the society. Although IDD is considered a natural process in degenerative lesions, it is mainly caused by aging, trauma, genetic susceptibility and other factors. It is closely related to changes in the tissue structure and function, including the progressive destruction of extracellular matrix, cell aging, cell death of the intervertebral disc (IVD), inflammation, and impairment of tissue biomechanical function. Currently, the treatment of IDD is aimed at alleviating symptoms rather than at targeting pathological changes in the IVD. Furthermore, the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling pathway is closely related to various pathological processes in IDD, and the activation of the MAPK/ERK pathway promotes the degradation of the IVD extracellular matrix, cell aging, apoptosis, and inflammatory responses. It also induces autophagy and oxidative stress that accelerate the IVD process. In our current review, we summarize the latest developments in the negative regulation of IDD after activation of the MAPK/ERK signaling pathway and emphasize on its influence on IDD. Targeting this pathway may become an attractive treatment strategy for IDD in the near future.

Functional changes in decidual mesenchymal stem/stromal cells are associated with spontaneous onset of labour

Ageing and parturition share common pathways, but their relationship remains poorly understood. Decidual cells undergo ageing as parturition approaches term, and these age-related changes may trigger labour. Mesenchymal stem/stromal cells (MSCs) are the predominant stem cell type in the decidua. Stem cell exhaustion is a hallmark of ageing, and thus ageing of decidual MSCs (DMSCs) may contribute to the functional changes in decidual tissue required for term spontaneous labour. Here, we determine whether DMSCs from patients undergoing spontaneous onset of labour (SOL-DMSCs) show evidence of ageing-related functional changes compared with those from patients not in labour (NIL-DMSCs), undergoing Caesarean section. Placentae were collected from term (37-40 weeks of gestation), SOL (n = 18) and NIL (n = 17) healthy patients. DMSCs were isolated from the decidua basalis that remained attached to the placenta after delivery. DMSCs displayed stem cell-like properties and were of maternal origin. Important cell properties and lipid profiles were assessed and compared between SOL- and NIL-DMSCs. SOL-DMSCs showed reduced proliferation and increased lipid peroxidation, migration, necrosis, mitochondrial apoptosis, IL-6 production and p38 MAPK levels compared with NIL-DMSCs (P < 0.05). SOL- and NIL-DMSCs also showed significant differences in lipid profiles in various phospholipids (phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylserine), sphingolipids (ceramide, sphingomyelin), triglycerides and acyl carnitine (P < 0.05). Overall, SOL-DMSCs had altered lipid profiles compared with NIL-DMSCs. In conclusion, SOL-DMSCs showed evidence of ageing-related reduced functionality, accumulation of cellular damage and changes in lipid profiles compared with NIL-DMSCs. These changes may be associated with term spontaneous labour.

TBX2, a Novel Regulator of Labour

Background and Objectives: Therapeutic interventions targeting molecular factors involved in the transition from uterine quiescence to overt labour are not substantially reducing the rate of spontaneous preterm labour. The identification of novel rational therapeutic targets are essential to prevent the most common cause of neonatal mortality. Based on our previous work showing that Tbx2 (T-Box transcription factor 2) is a putative upstream regulator preceding progesterone withdrawal in mouse myometrium, we now investigate the role of TBX2 in human myometrium. Materials and Methods: RNA microarray analysis of (A) preterm human myometrium samples and (B) myometrial cells overexpressing TBX2 in vitro, combined with subsequent analysis of the two publicly available datasets of (C) Chan et al. and (D) Sharp et al. The effect of TBX2 overexpression on cytokines/chemokines secreted to the myometrium cell culture medium were determined by Luminex assay. Results: Analysis shows that overexpression of TBX2 in myometrial cells results in downregulation of TNFα- and interferon signalling. This downregulation is consistent with the decreased expression of cytokines and chemokines of which a subset has been previously associated with the inflammatory pathways relevant for human labour. In contrast, CXCL5 (C-X-C motif chemokine ligand 5), CCL21 and IL-6 (Interleukin 6), previously reported in relation to parturition, do not seem to be under TBX2 control. The combined bioinformatical analysis of the four mRNA datasets identifies a subset of upstream regulators common to both preterm and term labour under control of TBX2. Surprisingly, TBX2 mRNA levels are increased in preterm contractile myometrium. Conclusions: We identified a subset of upstream regulators common to both preterm and term labour that are activated in labour and repressed by TBX2. The increased TBX2 mRNA expression in myometrium collected during a preterm caesarean section while in spontaneous preterm labour compared to tissue harvested during iatrogenic preterm delivery does not fit the bioinformatical model. We can only explain this by speculating that the in vivo activity of TBX2 in human myometrium depends not only on the TBX2 expression levels but also on levels of the accessory proteins necessary for TBX2 activity.

Late/post-term decidual basalis-derived mesenchymal stem/stromal cells show evidence of advanced ageing and downregulation of microRNA-516b-5p

INTRODUCTION

The placenta is a short-lived organ, yet it shows signs of progressive ageing in the third trimester. Studies of ageing chorionic placental tissue have recently flourished, providing evidence of advanced ageing of tissues in the late/post-term (L/PT) period of gestation. However, ageing of the maternal aspect of the maternal-fetal interface, specifically the decidua basalis, is poorly understood. Here, we investigated whether the L/PT period was associated with advanced ageing and exhaustion of important decidua basalis mesenchymal stem/stromal cells (DMSCs) functions.

METHODS

In this study, DMSCs were isolated and characterised from early term (ET) and L/PT placental tissue and they were then investigated by employing various MSC potency and ageing assays. RNA sequencing was also performed to screen for specific microRNAs that are associated with stem cell exhaustion and ageing between ET- and L/PT-DMSCs.

RESULTS

L/PT-DMSCs, when compared to ET-DMSCs, showed significantly lower cell proliferation and a significant higher level of cell apoptosis. L/PT-DMSCs showed significantly lower resistance to oxidative stress and a significant decrease in antioxidant capacity compared with ET-DMSCs. Western blot analysis revealed increased expression of the stress-mediated P-p38MAPK protein in L/PT-DMSCs. RNA Sequencing showed microRNA (miR) miR-516b-5p, was present at significantly lower levels in L/PT-DMSCs. Inhibition of miR-516b-5p in ET-DMSCs revealed a decline in the ability of the inhibited cells to survive in extended cell culture.

DISCUSSION

These data provide the first evidence of advanced ageing and exhaustion of important stem cell functions in L/PT-DMSCs, and the involvement of specific miRs in the DMSC ageing process.

Aerobic Vaginitis Induced by Escherichia coli Infection During Pregnancy Can Result in Adverse Pregnancy Outcomes Through the IL-4/JAK-1/STAT-6 Pathway

Aerobic vaginitis (AV) can occur if normal vaginal microflora are dominated by aerobic bacteria, seriously affects not only female health, but also fetal health while they are pregnant. Besides, pregnant status also aggravates the symptoms and consequences of the infection. Here, we infected pregnant BALB/c mice with Escherichia coli on embryonic day 4.5 (E4.5) (study group), and administered an equivalent volume of phosphate-buffered saline in another cohort of pregnant mice (control group). We recorded the weight of pregnant mice and their fetuses. The maternal and fetal weight of the study group decreased in comparison with that of the control group, whereas the weight of placenta increased in the study group. Then, five genes with significant upregulation and 15 genes with downregulation were screened. Expression of interleukin 4 (IL-4) mRNA in the study group decreased to 18.5%. Enzyme-linked immunosorbent assay results showed IL-4 expression in mouse plasma declined in the study group at E11.5 and E18.5. mRNA expression of chemokine (c-c motif) ligand (CCL)-17, CCL-22, CCL-24, IL-4, Janus Kinase (JAK)-1, signal transducer and activator of transcription (STAT)-6, and GATA-3 showed significant downregulation in placental and uterine tissues. Flow cytometry of primary decidual macrophages (DMs) revealed more M1-like macrophages in the study group. And after addition of IL-4 to DMs, more M1 macrophages polarized to M2 type macrophages. We did not discover bacteria existed in mouse placentas. Our study affords a feasible method for exploring and managing AV during pregnancy.

Sodium Hydrogen Exchanger Regulatory Factor-1 (NHERF1) Regulates Fetal Membrane Inflammation

The fetal inflammatory response, a key contributor of infection-associated preterm birth (PTB), is mediated by nuclear factor kappa B (NF-kB) activation. Na⁺/H⁺ exchanger regulatory factor-1 (NHERF1) is an adapter protein that can regulate intracellular signal transduction and thus influence NF-kB activation. Accordingly, NHERF1 has been reported to enhance proinflammatory cytokine release and amplify inflammation in a NF-kB-dependent fashion in different cell types. The objective of this study was to examine the role of NHERF1 in regulating fetal membrane inflammation during PTB. We evaluated the levels of NHERF1 in human fetal membranes from term labor (TL), term not in labor (TNIL), and PTB and in a CD1 mouse model of PTB induced by lipopolysaccharide (LPS). Additionally, primary cultures of fetal membrane cells were treated with LPS, and NHERF1 expression and cytokine production were evaluated. Gene silencing methods using small interfering RNA targeting NHERF1 were used to determine the functional relevance of NHERF1 in primary cultures. NHERF1 expression was significantly (p < 0.001) higher in TL and PTB membranes compared to TNIL membranes, and this coincided with enhanced (p < 0.01) interleukin (IL)-6 and IL-8 expression levels. LPS-treated animals delivering PTB had increased levels of NHERF1, IL-6, and IL-8 compared to phosphate-buffered saline (PBS; control) animals. Silencing of NHERF1 expression resulted in a significant reduction in NF-kB activation and IL-6 and IL-8 production as well as increased IL-10 production. In conclusion, downregulation of NHERF1 increased anti-inflammatory IL-10, and reducing NHERF1 expression could be a potential therapeutic strategy to reduce the risk of infection/inflammation associated with PTB.

Oxidative stress-induced downregulation of glycogen synthase kinase 3 beta in fetal membranes promotes cellular senescence†

OBJECTIVE

Oxidative stress (OS)-induced stress signaler p38 mitogen-activated protein kinase (p38MAPK) activation and fetal membrane senescence are associated with parturition. This study determined changes in glycogen synthase kinase 3 beta (GSK3β) and its regulation by p38MAPK in effecting senescence to further delineate the molecular mechanism involved in senescence.

METHODS

Primary human amnion epithelial cells and amnion mesenchymal cells were treated with cigarette smoke extract (CSE, OS inducer). Expression of total and phosphorylated GSK3β and p38MAPK, and that of GSK3β's downstream targets: beta-catenin (β-Cat) and nuclear factor erythroid 2-related factor 2 (Nrf2) (western blot analysis), cell cycle regulation and senescence (flow cytometry) were determined. The specificity of GSK3β and p38MAPK's mechanistic role was tested by co-treating cells with their respective inhibitors, CHIR99021 and SB203580. Exosomal secretion of β-Cat from OS-induced cells was confirmed by immunofluorescence confocal microscopy and western blot.

RESULTS

OS induced by CSE resulted in phosphorylation of GSK3β (inactivation) and p38MAPK (activation) that was associated with cell cycle arrest and senescence. Inhibitors to GSK3β and p38MAPK verified their roles. Glycogen synthase kinase 3 beta inactivation was associated with nuclear translocation of antioxidant Nrf2 and exosomal secretion of β-Cat.

CONCLUSIONS

OS-induced P-p38MAPK activation is associated with functional downregulation of GSK3β and arrest of cell cycle progression and senescence of amnion cells. Lack of nuclear translocation of β-Cat and its excretion via exosomes further supports the postulation that GSK3β down-regulation by p38MAPK may stop cell proliferation preceding cell senescence. A better understanding of molecular mechanisms of senescence will help develop therapeutic strategies to prevent preterm birth.

Small RNA (sRNA) expression in the chorioallantois, endometrium and serum of mares following experimental induction of placentitis

Intrauterine infection and inflammation remain a major cause of preterm labour in women and mares, with little known about small RNA (sRNA) expression in tissue or circulation. To better characterise placental inflammation (placentitis), we examined sRNA expression in the endometrium, chorioallantois and serum of mares with and without placentitis. Disease was induced in 10 mares via intracervical inoculation of Streptococcus equi ssp. zooepidemicus, either with moderate or high levels of inoculum; three uninoculated gestationally matched mares were used as controls. Matched chorioallantois and endometrium were sampled in two locations: Region 1, gross inflammation near cervical star with placental separation and Region 2, gross inflammation without placental separation. In Region 1, 26 sRNAs were altered in chorioallantois, while 20 were altered in endometrium. Within Region 2, changes were more subdued in both chorioallantois (10 sRNAs) and endometrium (two sRNAs). Within serum, we identified nine significantly altered sRNAs. In summary, we have characterised the expression of sRNA in the chorioallantois, the endometrium and the serum of mares with experimentally induced placentitis using next-generation sequencing, identifying significant changes within each tissue examined. These data should provide valuable information about the physiology of placental inflammation to clinicians and researchers alike.

Stretch, scratch, and stress: Suppressors and supporters of senescence in human fetal membranes

INTRODUCTION

Throughout gestation, amnion membranes undergo mechanical and or physiological stretch, scratch, or stress which is withstood by repairing and remodeling processes to protect the growing fetus. At term, increased oxidative stress (OS) activates p38MAPK, induces senescence, and inflammation contributing to membrane dysfunction to promote labor. However, the signaling initiated by stretch and scratch is still unclear. This study compares the induction of p38MAPK mediated senescence by stretch, scratch, and stress in human amnion epithelial cells (AECs).

METHODS

Primary AECs from term, not-in-labor, fetal membranes were cultured using the following conditions (N = 3); 1) CellFlex chambers with or without 20% biaxial stretch, 2) 8-well coverslips with or without scratch, and 3) cells exposed to cigarette smoke extract (CSE) inducing OS. p38MAPK (Western blot or immunocytochemistry), senescence activation, and inflammation (matrix metalloproteinases 9 [MMP9] activity-ELISA) were determined in cells exposed to various conditions. T-test and One-Way ANOVA was used to assess significance.

RESULTS

Biological membrane extension, mimicked by 20% biaxial stretch of AEC, maintained an epithelial morphology and activated P-p38MAPK (P = 0.02) compared to the non-stretch controls, but did not induce senescence or MMP9 activation. AEC scratches were healed within 40-hrs, which included proliferation, migration, and cellular transitions aided by p38MAPK activation but not senescence. CSE induced OS increased p38MAPK (P = 0.018) activation, senescence (P = 0.019), and MMP9 (P = 0.02).

CONCLUSION

Physiologic stretch and scratch experienced during gestation can cause p38MAPK activation without causing senescence or inflammation. This may be indicative of p38MAPK's role in tissue remodeling during pregnancy. Overwhelming OS, experienced at term, results in P-p38MAPK mediated senescence and inflammation to disrupt membrane remodeling.

Lactobacillus strains vary in their ability to interact with human endometrial stromal cells

The placental membranes that surround the fetus during pregnancy were suggested to contain a low abundance microbiota. Specifically, abundance of Lactobacillus, a probiotic and dominant member of the microbiome of the lower reproductive tract, has been shown to correlate with healthy, term pregnancies. We therefore sought to assess the interactions between four different Lactobacillus strains with immortalized decidualized endometrial cells (dT-HESCs), which were used as a model to represent the outermost layer of the placental membranes. Notably, we demonstrated that all four Lactobacillus strains could associate with dT-HESCs in vitro. L. crispatus was significantly more successful (p < 0.00005), with 10.6% of bacteria attaching to the host cells compared to an average of 0.8% for the remaining three strains. The four strains also varied in their ability to form biofilms. Dependent on media type, L. reuteri 6475 formed the strongest biofilms in vitro. To examine the impact on immune responses, levels of total and phosphorylated protein p38, a member of the Mitogen Activated Protein Kinase (MAPK) pathway, were examined following Lactobacillus association with dT-HESCs. Total levels of p38 were reduced to an average of 44% that of the cells without Lactobacillus (p < 0.05). While a trend towards a reduction in phosphorylated p38 was observed, this difference was not significant (p > 0.05). In addition, association with Lactobacillus did not result in increased host cell death. Collectively, these data suggest that varying types of Lactobacillus can attach to the outermost cells of the placental membranes and that these interactions do not contribute to inflammatory responses or host cell death. To our knowledge this is the first in vitro study to support the ability of Lactobacillus to interact with placental cells, which is important when considering its use as a potential probiotic within the reproductive tract.

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.

Involvement of p38 MAPK in Synaptic Function and Dysfunction

Many studies have revealed a central role of p38 MAPK in neuronal plasticity and the regulation of long-term changes in synaptic efficacy, such as long-term potentiation (LTP) and long-term depression (LTD). However, p38 MAPK is classically known as a responsive element to stress stimuli, including neuroinflammation. Specific to the pathophysiology of Alzheimer’s disease (AD), several studies have shown that the p38 MAPK cascade is activated either in response to the Aβ peptide or in the presence of tauopathies. Here, we describe the role of p38 MAPK in the regulation of synaptic plasticity and its implication in an animal model of neurodegeneration. In particular, recent evidence suggests the p38 MAPK α isoform as a potential neurotherapeutic target, and specific inhibitors have been developed and have proven to be effective in ameliorating synaptic and memory deficits in AD mouse models.

Interleukin (IL)-6: A Friend or Foe of Pregnancy and Parturition? Evidence From Functional Studies in Fetal Membrane Cells

Objective

Protection of the fetus within the amniotic sac is primarily attained by remodeling fetal membrane (amniochorion) cells through cyclic epithelial to mesenchymal and mesenchymal to epithelial (EMT and MET) transitions. Endocrine and paracrine factors regulate EMT and MET during pregnancy. At term, increased oxidative stress forces a terminal state of EMT and inflammation, predisposing to membrane weakening and rupture. IL-6 is a constitutively expressed cytokine during gestation, but it is elevated in term and preterm births. Therefore, we tested the hypothesis that IL-6 can determine the fate of amnion membrane cells and that pathologic levels of IL-6 can cause a terminal state of EMT and inflammation, leading to adverse pregnancy outcomes.

Methods

Primary amnion epithelial cells (AECs) were treated with recombinant IL-6 (330, 1,650, 3,330, and 16,000 pg/ml) for 48 h (N = 5). IL-6-induced cell senescence (aging), cell death (apoptosis and necrosis), and cell cycle changes were studied using flow cytometry. Cellular transitions were determined by immunocytochemistry and western blot analysis, while IL-6 signaling (activation of signaling kinases) was measured by immunoassay. Inflammatory marker matrix metalloproteinase (MMP9) and granulocyte-macrophage colony-stimulating factor (GM-CSF) concentrations were measured using a Fluorokine E assay and ELISA, respectively. Amniotic membranes collected on gestational day (D) 12 and D18 from IL-6 knockout (KO) and control C57BL/6 mice (N = 3 each) were used to determine the impact of IL-6 on cell transitions. Fold changes were measured based on the mean of each group.

Results

IL-6 treatment of AECs at physiologic or pathologic doses increased JNK and p38MAPK activation; however, the activation of signals did not cause changes in AEC cell cycle, cellular senescence, apoptosis, necrosis, cellular transitions, or inflammation (MMP9 and GM-CSF) compared to control. EMT markers were higher on D18 compared to D12 regardless of IL-6 status in the mouse amniotic sac.

Conclusion

Physiologic and pathologic concentrations of IL-6 did not cause amnion cell aging, cell death, cellular transitions, or inflammation. IL-6 may function to maintain cellular homeostasis throughout gestation in fetal membrane cells. Although IL-6 is a good biomarker for adverse pregnancies, it is not an indicator of an underlying pathological mechanism in membrane cells.

Systems Pharmacology-Based Research on the Mechanism of Tusizi-Sangjisheng Herb Pair in the Treatment of Threatened Abortion

Threatened abortion (TA) is a common complication with high incidence in the first trimester of pregnancy, which will end in miscarriage if not treated properly. The Chinese herbs Cuscutae Semen (Tusizi in Chinese) and Herba Taxilli (Sangjisheng in Chinese) first recorded in the ancient classic medical book Shennong Bencao Jing are effective and widely used as an herb pair for the treatment of TA, while the active ingredients and the functional mechanism of Tusizi-Sangjisheng herb pair treating TA are still unknown. In order to exploit the relationship between those two herbs and TA, systems pharmacology analysis was carried out in this study. A total of 75 ingredients of Tusizi-Sangjisheng were collected from Traditional Chinese Medicine System Pharmacology Database and Analysis Platform (TCMSP). 12 bioactive compounds were screened, and 153 directly related targets were predicted by systematic models. Besides, Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were used to systematically explore the potential mechanisms of Tusizi-Sangjisheng treating TA. Meanwhile, Compound-Target (C-T), Target-Disease (T-D), and Target-Pathway (T-P) networks were constructed to further quest the underlying functional mechanisms of Tusizi-Sangjisheng. As a result, 31 targets and 3 key pathways were found to be directly related to TA that includes mitogen-activated protein kinases (MAPKs), phosphatidylinositol-3-kinase/protein kinase B (PI3K-Akt), and transforming growth factor-β (TGF-β) signaling pathways. The results in this study may provide some valuable clues about the molecular mechanisms of the efficient Chinese herb pair Tusizi-Sangjisheng in the treatment of TA.

Neuregulin‑1: An underlying protective force of cardiac dysfunction in sepsis (Review)

Neuregulin-1 (NRG-1) is a type of epidermal growth factor-like protein primarily distributed in the nervous and cardiovascular systems. When sepsis occurs, the incidence of cardiac dysfunction in myocardial injury is high and the mechanism is complicated. It directly causes myocardial cell damage, whilst also causing damage to the structure and function of myocardial cells, weakening of endothelial function and coronary microcirculation, autonomic dysfunction, and activation of myocardial inhibitory factors. Studies investigating NRG-1 have been performed using a variety of methods, including in vitro models, and animal and human clinical trials; however, the results are not consistent. NRG-1/ErbBs signaling is involved in a variety of cardiac processes, from the development of the myocardium and cardiac conduction systems to the promotion of angiogenesis in cardiomyocytes, and in cardio-protective effects during injury. NRG-1 may exert a multifaceted cardiovascular protective effect by activating NRG-1/ErbBs signaling and regulating multiple downstream signaling pathways, thereby improving myocardial cell dysfunction in sepsis, and protecting cardiomyocytes and endothelial cells. It may alleviate myocardial microvascular endothelial injury in sepsis; its anti-inflammatory effects inhibit the production of myocardial inhibitory factors in sepsis, improve myocardial ischemia, decrease oxidative stress, regulate the disruption to the homeostasis of the autonomic nervous system, improve diastolic function, and offer protective effects at multiple target sites. As the mechanism of action of NRG-1 intersects with the pathways involved in the pathogenesis of sepsis, it may be applicable as a treatment strategy to numerous pathological processes in sepsis.

Reversible EMT and MET mediate amnion remodeling during pregnancy and labor

The amnion is remodeled during pregnancy to protect the growing fetus it contains, and it is particularly dynamic just before and during labor. By combining ultrastructural, immunohistochemical, and Western blotting analyses, we found that human and mouse amnion membranes during labor were subject to epithelial-to-mesenchymal transition (EMT), mediated, in part, by the p38 mitogen-activated protein kinase (MAPK) pathway responding to oxidative stress. Primary human amnion epithelial cell cultures established from amnion membranes from nonlaboring, cesarean section deliveries exhibited EMT after exposure to oxidative stress, and the pregnancy maintenance hormone progesterone (P4) reversed this process. Oxidative stress or transforming growth factor-β (TGF-β) stimulated EMT in a manner that depended on TGF-β-activated kinase 1 binding protein 1 (TAB1) and p38 MAPK. P4 stimulated the reverse transition, MET, in primary human amnion mesenchymal cells (AMCs) through progesterone receptor membrane component 2 (PGRMC2) and c-MYC. Our results indicate that amnion membrane cells dynamically transition between epithelial and mesenchymal states to maintain amnion integrity and repair membrane damage, as well as in response to inflammation and mechanical damage to protect the fetus until parturition. An irreversible EMT and the accumulation of AMCs characterize the amnion membranes at parturition.

Telomere Length and Telomerase Activity in Foetal Membranes from Term and Spontaneous Preterm Births

The reduction of telomere length, the protective cap structures of chromosomes, is one of the biomarkers of senescence (a mechanism of ageing), and ageing of foetal gestational tissues is associated with both term and preterm parturition. A mechanism regulating telomere length is the activity of telomerase, an enzyme that adds telomere fragments during DNA replication and cell division; however, its role in regulating telomere length is not well studied in gestational tissues. The objective of this study is to correlate telomere length and telomerase activity in foetal membranes from term and spontaneous preterm births. Foetal membrane samples were collected from pregnant women experiencing term labour (TL), term not in labour (TNL), preterm premature rupture of membranes (pPROM) and spontaneous preterm labour (PTL) with intact membranes (n = 20/group). Telomere length and telomerase activity were analyzed by relative quantification (T/S), real-time PCR and PCR-based fluorometric detection, respectively. Data were analyzed by ANOVA or the Kruskal-Wallis test. Demographic variables were not statistically different among the groups. Foetal membranes from the TL group showed telomere length reduction compared with those from the others (p < 0.0002). Telomerase activity did not change in foetal membranes irrespective of pregnancy outcome. Telomere shortening in foetal membranes is suggestive of senescence associated with triggering of labour at term; however, this is likely independent of telomerase activity, while prematurity may be associated with senescence, but due to other mechanisms than telomere length reduction in foetal membranes.

Increased Soluble Epoxide Hydrolase in Human Gestational Tissues from Pregnancies Complicated by Acute Chorioamnionitis

Chorioamnionitis (CAM) is primarily a polymicrobial bacterial infection involving chorionic and amniotic membranes that is associated with increased risk of preterm delivery. Epoxyeicosatrienoic acids (EETs) are eicosanoids generated from arachidonic acid by cytochrome P450 enzymes and further metabolized mainly by soluble epoxide hydrolase (sEH) to produce dihydroxyeicosatrienoic acids (DHETs). As a consequence of this metabolism of EETs, sEH reportedly exacerbates several disease states; however, its role in CAM remains unclear. The objectives of this study were to (1) determine the localization of sEH and compare the changes it undergoes in the gestational tissues (placentas and fetal membranes) of women with normal-term pregnancies and those with pregnancies complicated by acute CAM; (2) study the effects of lipopolysaccharide (LPS) on the expression of sEH in the human gestational tissues; and (3) investigate the effect of 12-(3-adamantan-1-yl-ureido)-dodecanoic acid (AUDA), a specific sEH inhibitor, on LPS-induced changes in 14,15-DHET and cytokines such as interleukin- (IL-) 1β and IL-6 in human gestational tissues in vitro and in pregnant mice. We found that women with pregnancies complicated by acute CAM had higher levels of sEH mRNA and protein in fetal membranes and villous tissues compared to those in women with normal-term pregnancies without CAM. Furthermore, fetal membrane and villous explants treated with LPS had higher tissue levels of sEH mRNA and protein and 14,15-DHET than those present in the vehicle controls, while the administration of AUDA in the media attenuated the LPS-induced production of 14,15-DHET in tissue homogenates and IL-1β and IL-6 in the media of explant cultures. Administration of AUDA also reduced the LPS-induced changes of 14,15-DHET, IL-1β, and IL-6 in the placentas of pregnant mice. Together, these results suggest that sEH participates in the inflammatory changes in human gestational tissues in pregnancies complicated by acute CAM.

TGF-β1 alleviates HgCl2 induced apoptosis via P38 MAPK signaling pathway in human trophoblast cells

It is well known that embryonic development can be perturbed by environmental factors such as heavy metals. Mercury is one of the most significant threats to the environment and human health. Mercury can damage many parts of the human body, including lungs, kidneys, nerves and fetus. However, the effect of mercury on human embryo remains unknown. Here, we showed that HgCl₂ treatment resulted in a significant increase in apoptosis in HTR-8/SVneo cells. However, the effect of HgCl₂ on apoptosis was partially reduced by the combination treatment with TGF-β1 and HgCl₂ in HTR-8/SVneo cells. Moreover, HgCl₂ treatment gradually decreased the expression of TGF-β1 in a dose dependent manner. Furthermore, a P38 MAPK inhibitor, SB202190, decreased the cell apoptosis and caspase activation induced by HgCl₂ in trophoblast cells. In addition, TGF-β1 alleviated HgCl₂ induced apoptosis of HTR-8/SVneo cells via p38 MAPK signaling pathway, which was involved in the TAK1 expression. These results might provide a theoretical basis for mercury induced trophoblast associated embryo damage and a potential avenue of intervention.

Immune tolerance attenuates gut dysbiosis, dysregulated uterine gene expression and high-fat diet potentiated preterm birth in mice

BACKGROUND

Preterm delivery accounts for 85% of perinatal morbidity and mortality. Although the consumption of a high-fat diet leads to exaggerated proinflammatory responses and, in pregnant women, increased rates of spontaneous preterm birth, the underlying mechanisms remain unclear.

OBJECTIVE

We sought to elucidate the mechanisms by which maternal consumption of a high-fat diet leads to a dysregulated immune response and, subsequently, spontaneous preterm birth.

STUDY DESIGN

We performed 16S ribosomal RNA sequencing of DNA extracted and amplified from stool samples and compared the gut microbiomes of lipopolysaccharide-induced pregnant mice that were maintained on a high-fat diet compared to a normal control diet. Next, we sequenced the uterine transcriptomes of the mice. To test the effect of dampening of the immune response on the microbiome, transcriptome, and risk of spontaneous preterm birth, we induced immune tolerance with repetitive subclinical doses (0.2 mg/kg/week for 8 weeks) of endotoxin and performed 16S ribosomal RNA and uterine transcriptome sequencing on these immunotolerized mice.

RESULTS

High-fat diet potentiates lipopolysaccharide-induced preterm birth by affecting the maternal gut microbiome and uterine transcriptome and reduces antioxidant capacity in a murine model. High-fat diet consumption also increases the colonization of the gut by 5 immunogenic bacteria and decreases colonization by Lachnospiraceae_NK4A136_group. Uteri from high-fat diet mice had increased expression of genes that stimulate the inflammatory-oxidative stress axis, autophagy/apoptosis, and smooth muscle contraction. Repetitive endotoxin priming protects high-fat diet dams from spontaneous preterm birth, increases colonization of the gut by Lachnospiraceae_NK4A136_group, decreases levels of immunogenic bacteria in the gut microbiome, and reduces the number of dysregulated genes after high-fat diet consumption from 994 to 74.

CONCLUSION

High-fat diet-potentiated spontaneous preterm birth is mediated by increased inflammation, oxidative stress, and gut dysbiosis. The induction of immune tolerance via endotoxin priming reverses these effects and protects high-fat diet dams from spontaneous preterm birth. Based on this work, the role of immunomodulation as a novel therapeutic approach to prevent preterm birth among women who consume high-fat diets should be explored.

Systematic review of p38 mitogen-activated kinase and its functional role in reproductive tissues

Oxidative stress (OS) plays a role in uterine tissue remodeling during pregnancy and parturition. While p38 MAPK is an OS-response kinase, a precise functional role is unknown. Therefore, we conducted a systematic review of literature on p38 MAPK expression, activation, and function in reproductive tissues throughout pregnancy and parturition, published between January 1980 and August 2017, using four electronic databases (Web of Science, PubMed, Medline, and CoCHRANE). We identified 418 reports; 108 were selected for full-text evaluation and 74 were included in final review. p38 MAPK was investigated using feto-maternal primary or immortalized cells, tissue explants, and animal models. Western blot was most commonly used to report phosphorylated (active) p38 MAPK. Human placenta (27), chorioamniotic membranes (14), myometrium (13), decidua (8), and cervix (1) were the studied tissues. p38 MAPK's functions were tissue and gestational age dependent. Isoform specificity was hardly reported. p38 MAPK activity was induced by ROS or proinflammatory cytokines to promote cell signaling linked to cell fate, primed uterus, ripened cervix, and proinflammatory cytokine/chemokine production. In 35 years, reports on p38 MAPK's role during pregnancy and parturition are scarce and current literature is insufficient to provide a comprehensive description of p38 MAPK's mechanistic role during pregnancy and parturition.

Oxidative stress-induced TGF-beta/TAB1-mediated p38MAPK activation in human amnion epithelial cells

Term and preterm parturition are associated with oxidative stress (OS)-induced p38 mitogen-activated protein kinase (p38MAPK)-mediated fetal tissue (amniochorion) senescence. p38MAPK activation is a complex cell- and stimulant-dependent process. Two independent pathways of OS-induced p38MAPK activation were investigated in amnion epithelial cells (AECs) in response to cigarette smoke extract (CSE: a validated OS inducer in fetal cells): (1) the OS-mediated oxidation of apoptosis signal-regulating kinase (ASK)-1 bound Thioredoxin (Trx[SH]2) dissociates this complex, creating free and activated ASK1-signalosome and (2) transforming growth factor-mediated activation of (TGF)-beta-activated kinase (TAK)1 and TGF-beta-activated kinase 1-binding protein (TAB)1. AECs isolated from normal term, not-in-labor fetal membranes increased p38MAPK in response to CSE and downregulated it in response to antioxidant N-acetylcysteine. In AECs, both Trx and ASK1 were localized; however, they remained dissociated and not complexed, regardless of conditions. Silencing either ASK1 or its downstream effectors (MKK3/6) did not affect OS-induced p38MAPK activation. Conversely, OS increased TGF-beta's release from AECs and increased phosphorylation of both p38MAPK and TAB1. Silencing of TAB1, but not TAK1, prevented p38MAPK activation, which is indicative of TAB1-mediated autophosphorylation of p38MAPK, an activation mechanism seldom seen. OS-induced p38MAPK activation in AECs is ASK1-Trx signalosome-independent and is mediated by the TGF-beta pathway. This knowledge will help to design strategies to reduce p38MAPK activation-associated pregnancy risks.

Association of single-nucleotide polymorphisms in NAT9 and MAP3K3 genes with litter size traits in Berkshire pigs

Litter size is an economically important trait in the pig industry. We aimed to identify genetic markers associated with litter size, which can be used in breeding programs for improving reproductive traits. Single-nucleotide polymorphisms (SNPs) of Berkshire pigs in the N-acetyltransferase 9 (NAT9) and Mitogen-activated protein kinase kinase kinase 3 (MAP3K3) genes were from RNA sequencing results, and already exist in the databank (NCBI), and were confirmed by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). A total of 272 Berkshire sows were used to examine the genotype, and their association with litter size traits was analyzed. The NAT9 SNP was located in chromosome 12 exon 640 mRNA (A > G) and the MAP3K3 SNP was located in chromosome 12 intron 11 (80, C > T). Association analysis indicated that the GG genotype of NAT9 and the CT genotype of MAP3K3 had the highest values for litter size traits. The GG genotype expressed higher levels of NAT9 mRNA in the endometrium than the other genotypes did, and a positive correlation was found between litter size traits and NAT9, but not MAP3K3 expression level. These results indicate that the NAT9 and MAP3K3 can be used as candidate genes applicable in breeding program for the improvement of litter size traits in Berkshire pigs.

A novel and compact review on the role of oxidative stress in female reproduction

In recent years, the study of oxidative stress (OS) has become increasingly popular. In particular, the role of OS on female fertility is very important and has been focused on closely. The occurrence of OS is due to the excessive production of reactive oxygen species (ROS). ROS are a double-edged sword; they not only play an important role as secondary messengers in many intracellular signaling cascades, but they also exert indispensable effects on pathological processes involving the female genital tract. ROS and antioxidants join in the regulation of reproductive processes in both animals and humans. Imbalances between pro-oxidants and antioxidants could lead to a number of female reproductive diseases. This review focuses on the mechanism of OS and a series of female reproductive processes, explaining the role of OS in female reproduction and female reproductive diseases caused by OS, including polycystic ovary syndrome (PCOS), endometriosis, preeclampsia and so on. Many signaling pathways involved in female reproduction, including the Keap1-Nrf2, NF-κB, FOXO and MAPK pathways, which are affected by OS, are described, providing new ideas for the mechanism of reproductive diseases.

Regulation of p38 mitogen-activated kinase-mediated fetal membrane senescence by statins

PROBLEM

Oxidative stress (OS)-induced, p38 mitogen-activated protein kinase (p38MAPK)-mediated chorioamniotic senescence and inflammation (senescence-associated secretory phenotype [SASP]) are associated with parturition. In response to OS-inducing risk factors, premature senescence contributes to preterm premature rupture of the membranes (pPROM) and spontaneous preterm birth (PTB). We determined the effect of simvastatin, rosuvastatin, and progesterone in downregulating p38MAPK-mediated senescence and SASP.

METHOD OF STUDY

Normal term, not-in-labor fetal membranes (n = 8) were exposed to cigarette smoke extract (CSE: OS inducer) alone or combined with simvastatin (100 and 200 ng/mL), rosuvastatin (100 and 200 ng/mL), and progesterone (10^-6  mol/L). p38MAPK expression changes were studied by Western blot, senescence was determined by senescence-associated β-Galactosidase (SA-β-Gal) staining, and multiplex analysis determined changes associated with 4 SASP markers (IL-8, IL-10, TNF-α, and GM-CSF). A pairwise comparison between groups was conducted by ANOVA.

RESULTS

Compared to untreated controls, CSE induced p38MAPK-mediated senescence and SASP. CSE cotreatment with simvastatin and rosuvastatin significantly reduced p38MAPK activation, senescence (decrease in SA-β-Gal) and SASP markers, GM-CSF, and TNF, but not IL-8, while increasing anti-inflammatory IL-10 in a dose-dependent manner. Cotreatment of CSE and progesterone had no effect on reducing p38MAPK activation, senescence, or SASP.

CONCLUSION

Both simvastatin and rosuvastatin downregulated OS-induced p38MAPK activation, senescence, and SASP, while rosuvastatin showed a pronounced effect. Progesterone did not reduce OS-induced fetal membrane senescence and SASP. Simvastatin or rosuvastatin may reduce the incidences of OS-associated PTB and pPROM by preventing premature senescence and SASP.

Oxygen concentration modulates cellular senescence and autophagy in human trophoblast cells

PROBLEM

We investigated the effect of oxygen concentrations on cellular senescence and autophagy and examined the role of autophagy in human trophoblast cells.

METHOD OF STUDY

Human first-trimester trophoblast cells (Sw.71) were incubated under 21%, 5%, or 1% O₂ concentrations for 24 hours. We examined the extent of senescence caused using senescence-associated β-galactosidase (SA-β-Gal) and senescence-associated secretory phenotype (SASP) as markers. Moreover, we examined the role of autophagy in causing cellular senescence using an autophagy inhibitor (3-methyladenine, 3MA).

RESULTS

Physiological normoxia (5% O₂ ) decreased SA-β-Gal-positive cells and SASP including interleukin-6 (IL-6) and IL-8 compared with cultured cells in 21% O₂ . Pathophysiological hypoxia (1% O₂ ) caused cytotoxicity, including extracellular release of ATP and lactate dehydrogenase, and decreased senescence phenotypes. 3MA-treated trophoblast cells significantly suppressed senescence markers (SA-β-Gal-positive cells and SASP secretion) in O₂ -independent manner.

CONCLUSION

We conclude that O₂ concentration modulates cellular senescence phenotypes regulating autophagy in the human trophoblast cells. Moreover, inhibiting autophagy suppresses cellular senescence, suggesting that autophagy contributes to oxygen stress-induced cellular senescence.

High-magnitude compression accelerates the premature senescence of nucleus pulposus cells via the p38 MAPK-ROS pathway

BACKGROUND

Mechanical overloading can lead to disc degeneration. Nucleus pulposus (NP) cell senescence is aggravated within the degenerated disc. This study was designed to investigate the effects of high compression on NP cell senescence and the underlying molecular mechanism of this process.

METHODS

Rat NP cells seeded in decalcified bone matrix were subjected to non-compression (control) or compression (2% or 20% deformation, 1.0 Hz, 6 hours/day). The reactive oxygen species (ROS) scavenger N-acetylcysteine (NAC) and the p38 MAPK inhibitor SB203580 were used to investigate the roles of the ROS and p38 MAPK pathway under high-magnitude compression. Additionally, we studied the effects of compression (0.1 or 1.3 MPa, 1.0 Hz, 6 hours/day) in a rat disc organ culture.

RESULTS

Both in scaffold and organ cultures, high-magnitude compression (20% deformation or 1.3 MPa) increased senescence-associated β-galactosidase (SA-β-Gal) activity, senescence marker (p16 and p53) expression, G1 cell cycle arrest, and ROS generation, and decreased cell proliferation, telomerase activity and matrix (aggrecan and collagen II) synthesis. Further analysis of the 20% deformation group showed that NAC inhibited NP cell senescence but had no obvious effect on phospho-p38 MAPK expression and that SB203580 significantly attenuated ROS generation and NP cell senescence.

CONCLUSIONS

High-magnitude compression can accelerate NP cell senescence through the p38 MAPK-ROS pathway.

Mapping out p38MAPK

To generate new hypotheses, sometimes a "systems" approach is needed. In this review, I focus on the mitogen-activated kinase p38 because it has been recently shown to play an important role in the developmental programing and senescence of normal and stressed reproductive tissues. What follows is an overview of (i) pathways of p38 activation and their involvement in basic biological processes, (ii) evidence that p38 is involved in the homeostasis of reproductive tissues, (iii) how focus on p38 can be incorporated into investigation of normal and stressed pregnancies. Existence of excellent reviews will be mentioned as well as relevant animal models.

Programmed Fetal Membrane Senescence and Exosome-Mediated Signaling: A Mechanism Associated With Timing of Human Parturition

Human parturition is an inflammatory process that involves both fetal and maternal compartments. The precise immune cell interactions have not been well delineated in human uterine tissues during parturition, but insights into human labor initiation have been informed by studies in animal models. Unfortunately, the timing of parturition relative to fetal maturation varies among viviparous species-indicative of different phylogenetic clocks and alarms-but what is clear is that important common pathways must converge to control the birth process. Herein, we hypothesize a novel signaling mechanism initiated by human fetal membrane aging and senescence-associated inflammation. Programmed events of fetal membrane aging coincide with fetal growth and organ maturation. Mechanistically, senescence involves in telomere shortening and activation of p38 mitogen-activated signaling kinase resulting in aging-associated phenotypic transition. Senescent tissues release inflammatory signals that are propagated via exosomes to cause functional changes in maternal uterine tissues. In vitro, oxidative stress causes increased release of inflammatory mediators (senescence-associated secretory phenotype and damage-associated molecular pattern markers) that can be packaged inside the exosomes. These exosomes traverse through tissues layers, reach maternal tissues to increase overall inflammatory load transitioning them from a quiescent to active state. Animal model studies have shown that fetal exosomes can travel from fetal to the maternal side. Thus, aging fetal membranes and membrane-derived exosomes cargo fetal signals to the uterus and cervix and may trigger parturition. This review highlights a novel hypothesis in human parturition research based on data from ongoing research using human fetal membrane model system.