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Human cytomegalovirus (CMV) is the most common cause of viral intrauterine infection in developed countries. It has been shown that CMV DNA was frequently detected in the fetal membranes when the placenta was infected in utero. However, it is still not clear whether CMV replicates in constituent cells of the fetal membranes. We investigated CMV infection of primary cultured chorion and amnion cells prepared from human fetal membrane tissues. In both types of cell cultures, rounded cells were observed at day 8 and 12 after CMV inoculation, and virus yields in culture supernatants were increased after the inoculation. In both types of cells, viral immediately early 1 (IE1) protein-positive nuclei were scattered at day 4 after the inoculation, and IE1 mRNA was expressed throughout day 1 to 12 after CMV inoculation. In chorion cell cultures, the number of IE1 protein-positive nuclei increased significantly at day 8 and 12 after CMV inoculation as compared to day 4, by which foci were formed. Furthermore, an evident increase in levels of lactate dehydrogenase leakage from chorion cells was observed after CMV inoculation. Contrary, these phenomena were not observed in amnion cell cultures. These results demonstrated that both chorion and amnion cells were permissive to CMV infection, while the velocity of cell-to-cell spread of CMV infection in amnion cells was much lower than that in chorion cells. Therefore, the present study suggests that CMV may replicate rapidly in the chorion cell layer and slowly in the amnion cell layer during intrauterine infection.

Arsenic trioxide (arsenite, As(III)) has shown a remarkable clinical efficacy, whereas its side effects are still a serious concern. Therefore, it is critical to understand the effects of As(III) on human-derived normal cells for revealing the mechanisms underlying these side effects. We examined the effects of As(III) on primary cultured chorion (C) and amnion (A) cells prepared from human fetal membranes. A significant dose-dependent As(III)-mediated cytotoxicity was observed in the C-cells accompanied with an increase of lactate dehydrogenase (LDH) release. Higher concentrations of As(III) were required for the A-cells to show cytotoxicity and LDH release, suggesting that the C-cells were more sensitive to As(III) than the A-cells. The expression levels of aquaporin 9 (AQP9) were approximately 2 times higher in the C-cells than those in the A-cells. Both intracellular arsenic accumulation and its cytotoxicity in the C-cells were significantly abrogated by sorbitol, a competitive AQP9 inhibitor, in a dose-dependent manner. The protein expression levels of multidrug resistance-associated protein (MRP) 2 were downregulated by As(III) in the C-cells, but not in the A-cells. No significant differences in the expression levels of MRP1 were observed between C- and A-cells. The protein expression of P-glycoprotein (P-gp) was hardly detected in both cells, although a detectable amount of its mRNA was observed. Cyclosporine A, a broad-spectrum inhibitor for ABC transporters, and MK571, a MRP inhibitor, but not PGP-4008, a P-gp specific inhibitor, potently sensitized both cells to As(III)-mediated cytotoxicity. These results suggest that AQP9 and MRP2 are involved in controlling arsenic accumulation in these normal cells, which then contribute to differential sensitivity to As(III) cytotoxicity between these cells., (Copyright © 2011 Elsevier Inc. All rights reserved.)

We have previously demonstrated that apoptosis induction is observed only in smooth chorion laeve trophoblast cells, and not in amnion epithelial cells of human fetal membrane tissues prepared at the term. Apoptosis induction was suppressed by the presence of an inhibitor specific for inducible nitric oxide synthase (iNOS), suggesting that intracellular oxidative stress plays a critical role in this process. In this study, we transfected the iNOS gene into primary cultured chorion and amnion cells to examine the direct contribution of iNOS gene expression to the apoptosis induction in these cells. We identified a significant increase in the levels of iNOS protein expression and nitrite accumulation in both chorion and amnion cells after the iNOS gene transfection. However, the induction of apoptosis was observed in an approximately 70% of chorion cells transfected with iNOS gene. Transfection of the iNOS gene into chorion cells resulted in the activation of p38 mitogen-activated protein kinase (MAPK) and downregulation of hemeoxygenase-1 protein expression, whereas no such events were observed in the transfected amnion cells. These results suggest that apoptosis induced in the chorion trophoblast cells by the iNOS gene expression is closely linked to a physiological consequence, such as the rupture of fetal membranes.

We have previously demonstrated that induction of apoptosis was observed in the smooth chorion trophoblast cells of human fetal membranes prepared at term, and that apoptosis progressed rapidly during in vitro incubation of the tissues. Furthermore, we identified the contribution of ROS production system (e.g., oxidant enzymes, such as iNOS and Cox-2) to the apoptosis induction in the chorion cells, suggesting an important role of the two inducible enzymes in the induction process. In this study, we examined the role of ROS elimination system (e.g., antioxidant enzymes, such as glutathione peroxidase (GPx) and catalase) in the apoptosis induction of the chorion cells, since the apoptosis induction by oxidative stress is a result of imbalance between production and elimination of ROS. Treatment of chorion and amnion cells with mercaptosuccinic acid (MS, GPx inhibitor) and 3-amino-1,2,4-triazole (ATZ, catalase inhibitor) resulted in an inhibition of GPx and catalase activity, respectively. Furthermore, incubation with MS alone induced apoptosis in the chorion cells and apoptosis level was enhanced by the addition of ATZ, while ATZ alone hardly induced apoptosis in the chorion cells. However, none of these reagents induced apoptosis in the amnion cells. Moreover, an increase of the level of hemeoxygenase-1 gene expression was observed only in the amnion cells when both antioxidant enzyme activities were suppressed. Therefore, we concluded that GPx played a more critical role than catalase in the control of the apoptosis induction of the chorion cells, suggesting that the threshold levels of stress tolerance in the chorion cells are much lower than those in the amnion cells.

Objectives: We investigated the involvement of p38 mitogen-activated protein (MAP) kinase in tumor necrosis factor (TNF)-alpha gene expression, apoptosis induction and virus replication in cultured human fetal membrane chorion cells infected with influenza virus., Methods: Influenza virus-infected chorion cells were incubated in the absence or presence of inhibitors of p38 MAP kinase, SB203580 and SB202190. TNF-alpha mRNA and hemagglutinin viral RNA (HA vRNA) were amplified with reverse transcriptase-polymerase chain reaction techniques. TNF-alpha protein concentrations were determined by enzyme-liked immunosorbent assay. The extent of apoptosis induction was estimated by DNA agarose gel electrophoresis. Pyrrolidine dithiocarbamate (PDTC) and ribavirin, which have been shown to inhibit apoptosis induction via the inhibition of viral gene replication, were used as positive control reagents., Results: PDTC and ribavirin inhibited the accumulation of TNF-alpha mRNA and HA vRNA in the virus-infected chorion cells, resulting in the suppression of TNF-alpha protein secretion. Both SB203580 and SB202190 suppressed TNF-alpha protein secretion, but not the accumulation of TNF-alpha mRNA as well as HA vRNA and the induction of apoptosis., Conclusions: These results suggest that p38 MAP kinase pathway is critical in TNF-alpha gene expression at a post-transcriptional level but not in the apoptosis induction and influenza virus replication in cultured chorion cells., (2007 S. Karger AG, Basel)

We examined the contribution of apoptosis- and oxidative stress-associated genes to apoptosis induction in trophoblast cells of human fetal membrane tissues undergoing apoptosis during in vitro incubation. RT-PCR analyses demonstrated an increased level of HO-1, Mn-SOD, Cox-2, iNOS, TNFalpha, TNFR1, IL-1beta, IL-6, Bax, Bak, and Bad gene expression, while Bcl-2 mRNA expression level decreased. Western blot analyses demonstrated an increase in iNOS, Cox-2, and HO-1 protein levels; a decrease in pro-caspase-3 and 9, proform-PARP, and Apaf-1 protein levels; a leakage of cytochrome c from the mitochondria. An antioxidative reagent, general and selective Cox-2 inhibitors, and an iNOS inhibitor suppressed in vitro progression of the apoptosis. Furthermore, an NO donor reagent induced apoptosis in primary cultured trophoblast cells. Therefore, we concluded that the induction of apoptosis in the smooth chorion trophoblasts is mediated through oxidative stress induction followed by mitochondria damage, suggesting that iNOS and Cox-2 play an important role in the apoptosis induction in trophoblasts of human fetal membrane tissues.

Influenza virus infection during pregnancy has been implicated as one of cause of premature delivery, abortion and stillbirth. We have reported that cultured human fetal membrane chorion cells undergoing apoptosis by influenza virus infection secrete unidentified heat-stable monocyte differentiation-inducing (MDI) factors. In this study, cellular, biological and immunochemical characteristics of MDI factors were investigated using human monocytic leukemia THP-1 cells by nitroblue tetrazolium reduction and cell adhesion assays. The treatment of THP-1 cells with culture supernatants from the influenza virus-infected chorion cells induced the nitroblue tetrazolium reduction ability, which was inhibited by the addition of superoxide dismutase and diphenyleneiodonium chloride, an inhibitor for reduced nicotinamide adenine dinucleotide phosphate oxidase. The phenomenon was also observed in human peripheral blood monocytes and histiocytic leukemia U937 cells, but not in promyelocytic leukemia HL-60 cells. The induction of nitroblue tetrazolium reduction and adhesion abilities in THP-1 cells was closely correlated with the concentrations of interleukin-6 protein in the culture supernatants. These abilities were inhibited to approximately 60% by the addition of antibodies against interleukin-6, or alpha-chain (gp80) or beta-chain (gp130) of IL-6 receptor. The induction of nitroblue tetrazolium reduction was increased by the addition of supernatants from amniochorion tissue cultures after influenza virus infection. These results indicate that chorion cell-derived interleukin-6 is partly responsible for monocyte differentiation to macrophages capable of generating superoxide anion. It is possible that these pathways represent part of the mechanism for birth complications associated with intrauterine influenza infection in pregnancy.

Objectives: It has been postulated that the pathogenesis of influenza virus infection involves not only the virus-proliferation-mediated apoptotic cell death in infected cells, but also a direct reactive oxygen species (ROS)-induced cellular injury in the infected organs. We examined effects of an antioxidant, nordihydroguaiaretic acid (NDGA), on apoptosis induction and viral proliferation. Subsequently, the results were compared with those of pyrrolidine dithiocarbamate (PDTC), another antioxidant., Methods: The levels of ROS production were measured with 2',7'-dichlorofluorescein diacetate; apoptosis induction and viral proliferation were analyzed by DNA fragmentation and plaque-forming assays, respectively., Results: The treatment of infected cells with NDGA inhibited ROS overproduction, apoptotic DNA fragmentation and virus proliferation. The maximum inhibition against DNA fragmentation (76%) was observed with 500 microM NDGA. The antiviral activity of NDGA against influenza virus was more potent than that of PDTC., Conclusions: The present study, therefore, suggests for the first time that NDGA, a known antioxidant reagent, inhibits the induction of apoptosis in human fetal membrane chorion cells infected with influenza virus through the more potent antiviral activity than that of PDTC., (Copyright 2005 S. Karger AG, Basel)

Objective: In order to elucidate the implication of apoptosis in lactate dehydrogenase (LDH) leakage from influenza virus-infected cells, the effects of a general caspase inhibitor, N-t-Boc-Asp(OMe)-fluoromethylketone (Boc-D-fmk), on LDH leakage, apoptosis induction and virus proliferation were examined. Methods: Cultured human fetal membrane chorion and amnion cells were incubated with or without Boc-D-fmk after influenza virus infection. LDH leakage was estimated by measuring LDH activities in the culture supernatants and cell lysates. The extent of apoptosis was determined by caspase-3 protein cleavage and DNA fragmentation. Virus proliferation was determined by a plaque-forming assay. Results: While virus proliferation was observed in both chorion and amnion cells, the virus infection resulted in LDH leakage, caspase-3 protein cleavage, and oligonucleosomal DNA fragmentation, all of which were observed only in the chorion cells and inhibited by the presence of Boc-D-fmk except for the virus proliferation. Conclusion: LDH level in amniotic fluid is known to be one of markers for predicting fetal membrane damage. Therefore, this study provides a possible diagnostic application of LDH level to predict the extent of tissue damage of fetal membranes via apoptosis induced by influenza virus infection. Copyright © 2009 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]