Increased expression of sphingosine kinase in the amnion during labor

Sphingosine 1-Phosphate Activates S1PR3 to Induce a Proinflammatory Phenotype in Human Myometrial Cells

One of the common mechanisms responsible for obstetric complications, affecting millions of women every year, is abnormal uterine contractility. Despite the critical importance of this process for women's health, the mechanisms of uterine contraction regulation remain poorly understood. The initiation of uterine smooth muscle (myometrial) contraction is an inflammatory process, accompanied by upregulation of proinflammatory genes and cytokine release. In this study, we show that sphingolipid metabolism is activated during human labor and that sphingosine 1-phosphate (S1P), the main bioactive sphingolipid, may modify the myometrial proinflammatory phenotype. Our data in both primary and immortalized human myometrial cells show that exogenous S1P induces a proinflammatory gene signature and upregulates the expression of known inflammatory markers of parturition, such as IL8 and COX2. Using expression of IL8 as a readout for S1P activity in myometrial cells, we established that these S1P effects are mediated through the activation of S1P receptor 3 (S1PR3) and downstream activation of ERK1/2 pathways. Inhibition of S1PR3 in human myometrial cells attenuates upregulation of IL8, COX2, and JUNB both at the mRNA and protein levels. Furthermore, activation of S1PR3 with a receptor-specific agonist recapitulated the effects seen after treatment with exogenous S1P. Collectively, these results suggest a signaling pathway activated by S1P in human myometrium during parturition and propose new targets for development of novel therapeutics to alter uterine contractility during management of preterm labor or labor dystocia.

Gestational tissue inflammatory biomarkers at term labor: A systematic review of literature

Parturition at term is characterized by inflammatory overload in both feto-maternal tissues. Despite the large number of individual studies on changes in inflammatory biomarkers linked to labor, a comprehensive profile of them in each of the uterine compartments is not available to better understand their mechanistic contributions to labor. This systematic review investigated the pro- and anti-inflammatory biomarkers reported in intra-uterine tissues (amnion, chorion, decidua, placenta, and myometrium) at term labor. We conducted a systematic review of studies on pro- and anti-inflammatory biomarkers (mRNA and/or protein) reported in feto-maternal tissues during normal human term labor, published in English (1980-2016), in 3 electronic data bases. From a total of 3712 citations, 172 were included for final review. Each tissue expresses a unique set of biomarkers at the time of term labor, but there is significant overlap between tissues. All tissues had IL-6, IL-8, IL-1β, COX-2, PGE-2, TNF-α, and hCAP18 in common at term labor. Common and unique inflammatory biomarkers are expressed in various feto-maternal compartments at term labor. Increase in pro-inflammatory markers in all gestational tissue signifies their harmonious functional role in promoting labor. Anti-inflammatory markers at term labor are hardly reported.

The expression of Toll-like receptor 5 in preterm histologic chorioamnionitis

Spontaneous preterm birth is often caused by chorioamnionitis. Toll-like receptors (TLRs) have a role in the response of the innate immune system. The role of TLR5 in chorioamnionitis remains unclear: however, TLR5 was reported to have a significantly stronger effect on the induction of interleukin (IL)-6 when compared with other TLRs in amniotic epithelial cells. The aim of this study was to investigate TLR5 expression in placentas with preterm histologic chorioamnionitis (HCA). The expression levels of TLR5 were evaluated in the amnions, chorions, deciduae and villi with and without HCA using immunohistochemistry. The co-localization of IL-6 or IL-8 with TLR5 was examined by immunofluorescence. The production of IL-6 was examined in primary tissue cultured fetal membranes treated with and without the TLR5 agonist. The protein expression of TLR5 was significantly increased in amnions with HCA (p<0.05) and showed a trend toward an increase in chorions with HCA, whereas no significant difference was detected in the villi and decidua. TLR5 co-localized with IL-6 and IL-8 in amnions and chorions. IL-6 showed a significant increase (p<0.05) with the TLR5 agonist. These results suggest that TLR5 plays a role in the pathogenesis of preterm HCA and IL-6 production.

Neuroprotective potential of molecular hydrogen against perinatal brain injury via suppression of activated microglia

Exposure to inflammation in utero is related to perinatal brain injury, which is itself associated with high rates of long-term morbidity and mortality in children. Novel therapeutic interventions during the perinatal period are required to prevent inflammation, but its pathogenesis is incompletely understood. Activated microglia are known to play a central role in brain injury by producing a variety of pro-inflammatory cytokines and releasing oxidative products. The study is aimed to investigate the preventative potential of molecular hydrogen (H2), which is an antioxidant and anti-inflammatory agent without mutagenicity. Pregnant ICR mice were injected with lipopolysaccharide (LPS) intraperitoneally on embryonic day 17 to create a model of perinatal brain injury caused by prenatal inflammation. In this model, the effect of maternal administration of hydrogen water (HW) on pups was also evaluated. The levels of pro-inflammatory cytokines, oxidative damage and activation of microglia were determined in the fetal brains. H2 reduced the LPS-induced expression of pro-inflammatory cytokines, oxidative damage and microglial activation in the fetal brains. Next, we investigated how H2 contributes to neuroprotection, focusing on microglia, using primary cultured microglia and neurons. H2 prevented LPS- or cytokine-induced generation of reactive oxidative species by microglia and reduced LPS-induced microglial neurotoxicity. Finally, we identified several molecules influenced by H2, involved in the process of activating microglia. These results suggested that H2 holds promise for the prevention of inflammation related to perinatal brain injury.

Telomere Fragment Induced Amnion Cell Senescence: A Contributor to Parturition?

Oxidative stress (OS)-induced senescence of the amniochorion has been associated with parturition at term. We investigated whether telomere fragments shed into the amniotic fluid (AF) correlated with labor status and tested if exogenous telomere fragments (T-oligos) could induce human and murine amnion cell senescence. In a cross-sectional clinical study, AF telomere fragment concentrations quantitated by a validated real-time PCR assay were higher in women in labor at term compared to those not in labor. In vitro treatment of primary human amnion epithelial cells with 40 μM T-oligos ([TTAGGG]₂) that mimic telomere fragments, activated p38MAPK, produced senescence-associated (SA) β-gal staining and increased interleukin (IL)-6 and IL-8 production compared to cells treated with complementary DNA sequences (Cont-oligos, [AATCCC]₂). T-oligos injected into the uteri of pregnant CD1 mice on day 14 of gestation, led to increased p38MAPK, SA-β-gal (SA β-gal) staining in murine amniotic sacs and higher AF IL-8 levels on day 18, compared to saline treated controls. In summary, term labor AF samples had higher telomere fragments than term not in labor AF. In vitro and in situ telomere fragments increased human and murine amnion p38MAPK, senescence and inflammatory cytokines. We propose that telomere fragments released from senescent fetal cells are indicative of fetal cell aging. Based on our data, these telomere fragments cause oxidative stress associated damages to the term amniotic sac and force them to release other DAMPS, which, in turn, provide a sterile immune response that may be one of the many inflammatory signals required to initiate parturition at term.

Emerging roles for lysophospholipid mediators in pregnancy

Recent progress in lipid research has unveiled new biologic roles for lysophospholipids as mediators of intercellular signaling. Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) are representative lysophospholipids. Accumulating evidence suggests that, acting as intercellular mediators, these and other lysophospholipids may play important roles in physiological and pathological situations. This review discusses the possible involvement of LPA and S1P in reproductive processes, with a focus on the regulatory mechanisms of pregnancy maintenance. As LPA promotes prostaglandin synthesis, mediators in the LPA pathway may also play a significant role in implantation and parturition. S1P signaling is thought to be essential in vascular formation within the uteroplacental unit and in fetomaternal immunologic interactions. Derangements in either one of these lysophospholipid signaling pathways could result in pregnancy complications that may include implantation failure, preeclampsia, and preterm labor.

Gene expression analysis of the microdissected trophoblast layer of human placenta after the spontaneous onset of labor

Background

Despite increasing evidence that human parturition is associated with alteration in gene expression in the uteroplacental unit, the precise mechanisms that elicit spontaneous term labor in humans remain unknown. Our goal in this study was to compare the mRNA expression pattern of the trophoblast layer of normal term placenta between women who had given natural birth (labor group) and those who had undergone an elective cesarean section without labor (non-labor group).

Methods

We collected placental tissue samples from six pregnant women after term vaginal deliveries (labor group) and from six pregnant women after scheduled Cesarean sections (non-labor group). Frozen sections were made immediately after placental delivery. Because the placenta is a heterogeneous tissue composed of several cell types, we used laser capture microdissection to separate the trophoblast layer from the rest of the placental tissues.

Results

A number of genes were differentially expressed in the trophoblast layer when the labor and non-labor groups were compared. The expression of SIRT1, KAP1, and CRH was significantly lower in the trophoblast layer of the labor group than of the non-labor group. The expression of IL-1b, NF-kB1 and TLR 8 in the labor group was significantly higher than that in the non-labor group.

Conclusions

Human term labor may be closely associated with inflammatory response. We suggest that downregulation of SIRT1, KAP1, and CRH gene expression in the trophoblast may play a key role in parturition and initiation of labor in pregnant human females.