Secretion of bioactive interleukin-6 and tumor necrosis factor-alpha proteins from primary cultured human fetal membrane chorion cells infected with influenza virus

Maternal Influenza and Offspring Neurodevelopment

This review examines the complex interactions between maternal influenza infection, the immune system, and the neurodevelopment of the offspring. It highlights the importance of high-quality studies to clarify the association between maternal exposure to the virus and neuropsychiatric disorders in the offspring. Additionally, it emphasizes that the development of accurate animal models is vital for studying the impact of infectious diseases during pregnancy and identifying potential therapeutic targets. By drawing attention to the complex nature of these interactions, this review underscores the need for ongoing research to improve the understanding and outcomes for pregnant women and their offspring.

Culture of Human Fetal Membranes in a Two Independent Compartment Model: An Ex Vivo Approach

During pregnancy, the fetal membranes composed of the amnion and chorodecidua constitute a selective barrier separating two distinct environments, maternal and fetal. These tissues have the function of delimiting the amniotic cavity. Their histological complexity gives them physical, mechanical, and immunological properties to protect the fetus. Although the study of the amnion, chorion, and decidua separately provides knowledge about the functions of the fetal membranes, the protocol we describe in this chapter has the advantage of maintaining the biological and functional complexity of these tissues. In addition, this experimental model allows the researcher to recreate various pathological scenarios because this model allows for differential stimulation of the amnion or choriodecidua.

Hepatitis A virus cellular receptor 2 (HAVCR2) is decreased with viral infection and regulates pro-labour mediators OA

PROBLEM

Intrauterine infection caused by viral infection has been implicated to contribute to preterm birth. Hepatitis A virus cellular receptor 2 (HAVCR2) regulates inflammation in non-gestational tissues in response to viral infection.

METHOD OF STUDY

The aims of this study were to determine the effect of: (i) viral dsRNA analogue polyinosinic:polycytidylic acid (poly(I:C)) on HAVCR2 expression; and (ii) HAVCR2 silencing by siRNA (siHAVCR2) in primary amnion and myometrial cells on poly(I:C)-induced inflammation.

RESULTS

In human foetal membranes and myometrium, HAVCR2 mRNA and protein expression was decreased when exposed to poly(I:C). Treatment of primary amnion and myometrial cells with poly(I:C) significantly increased the expression and release of pro-inflammatory cytokines TNF, IL1A, IL1B and IL6; the expression of chemokines CXCL8 and CCL2; the expression and secretion of adhesion molecules ICAM1 and VCAM1; and PTGS2 and PTGFR mRNA expression and the release of prostaglandin PGF_2α . This increase was significantly augmented in cells transfected with siHAVCR2. Furthermore, mRNA expression of anti-inflammatory cytokines IL4 and IL10 was significantly decreased.

CONCLUSION

Collectively, our data suggest that HAVCR2 regulates cytokines, chemokines, prostaglandins and cell adhesion molecules in the presence of viral infection. This suggests a potential for HAVCR2 activators as therapeutics for the management of preterm birth associated with viral infections.

Regulation of Matrix Metalloproteinases-2 and -9 Gene Expression in Cultured Human Fetal Membrane Cells by Influenza Virus Infection

In order to understand a possible etiology of adverse pregnancy outcomes associated with intrauterine influenza virus infection, we examined the effect of influenza virus infection on gene expression of matrix metalloproteinases (MMPs) in cultured amnion epithelial, amnion mesenchymal and chorion trophoblast cells prepared from human fetal membrane tissues by gelatin zymography, Western blotting and reverse transcriptase-PCR. The cells were infected with influenza A (H1N1) virus. The levels of pro-MMP-9 activity in culture supernatants of three types of cells were increased during the period of 24-48 h after the virus infection as compared to those of mock infection. Chorion trophoblast cells spontaneously released a much greater level of pro-MMP-2 activity than amnion epithelial and amnion mesenchymal cells. The cleavage of pro-MMP-2 into an active intermediate form was enhanced in chorion trophoblast cells by the virus infection. The activity levels of MMP-2 and MMP-9 in culture supernatants were consistent with their protein levels. The virus infection induced the mRNA expression of MMP-9, but not MMP-2, in three types of cells. These results suggest that influenza virus infection induces the gene expression of MMP-9 and the cleavage of pro-MMP-2 into an active intermediate form in human fetal membrane cells, resulting in weakening of the membranes through extracellular matrix degradation. Therefore, it is possible that the regulation of MMPs gene expression in fetal membrane cells by influenza virus infection is implicated in a part of the etiology of adverse pregnancy outcomes associated with intrauterine infection with the virus.

Expression of tumor necrosis factor-alpha and vascular endothelial growth factor in different zones of fetal membranes: a possible relation to onset of labor

This study aimed to explore whether the altered expression of tumor necrosis factor-alpha (TNF-α), vascular endothelial growth factor (VEGF) and apoptotic changes in mid zone (MZ) and rupture zone (RZ) of fetal membranes (FM) are regulatory mechanisms associated with labor at term. Fifteen FM specimens were collected after vaginal deliveries and 13 specimens after elective caesarian section. Histological and immunohistochemical analysis were employed. Area percent of TNF-α and VEGF immunostaining and apoptotic index (AI) were evaluated using image analysis. The statistical data revealed significantly higher area % for TNF-α, VEGF immunoexpression and AI in labor compared to non-labor specimens (p < 0.0001). There was a significantly higher percentage of TNF-α immunoexpressed area in MZ compared with RZ in both groups (p < 0.0001). VEGF expression in RZ of both groups proved nearly double or triple the area % of expression relative to MZ with highly significant difference (p < 0.0001). quantitative analysis revealed near two fold increase in the AI in RZ (13.42% ± 1.2 in labor; 11.20% ± 0.96 in non-labor groups) when compared to MZ (7.20% ± 0.6 in labor; 5.08% ± 0.76 in non-labor groups) with highly significant zonal difference (p < 0.0001). Correlation analysis revealed significant correlation between apoptotic indices and area % of TNF-α (r = 0.575, p = 0.002 in non-labor; r = 0.652, p < 0.0001 in labor) and VEGF (r = 0.795, p < 0.0001 in non-labor; r = 0.668, p < 0.0001 in labor). In conclusion, Apoptosis may be regulated by TNF-α and VEGF expression in FM at labor. MZ is a step back from RZ and could participate actively in rupture of the FM during labor. TNF-α and VEGF increase with onset of labor and differentially expressed in the RZ and the MZ. These findings call for further study with tissue cultures or animal models.

Differences in permissive cytomegalovirus infection between primary cultured human fetal membrane chorion and amnion cells

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.

Influenza, immune system, and pregnancy

Influenza is a major health problem worldwide. Both seasonal influenza and pandemics take a major toll on the health and economy of our country. The present review focuses on the virology and complex immunology of this RNA virus in general and in relation to pregnancy. The goal is to attempt to explain the increased morbidity and mortality seen in infection during pregnancy. We discuss elements of innate and adaptive immunity as well as placental cellular responses to infection. In addition, we delineate findings in animal models as well as human disease. Increased knowledge of maternal and fetal immunologic responses to influenza is needed. However, enhanced understanding of nonimmune, pregnancy-specific factors influencing direct interaction of the virus with host cells is also important for the development of more effective prevention and treatment options in the future.

Single- and double-stranded viral RNA generate distinct cytokine and antiviral responses in human fetal membranes

There has been growing interest in the role of viral infections and their association with adverse pregnancy outcomes. However, little is known about the impact viral infections have on the fetal membranes (FM). Toll-like receptors (TLR) are thought to play a role in infection-associated inflammation at the maternal-fetal interface. Therefore, the objective of this study was to characterize the cytokine profile and antiviral response in human FMs exposed to viral dsRNA, which activates TLR3, and viral ssRNA, which activates TLR8; and to determine the mechanisms involved. The viral dsRNA analog, Poly(I:C), induced up-regulated secretion of MIP-1α, MIP-1β, RANTES and TNF-α, and down-regulated interleukin (IL)-2 and VEGF secretion. In contrast, viral ssRNA induced a broader panel of cytokines in the FMs by up-regulating the secretion of IL-1β, IL-2, IL-6, G-CSF, MCP-1, MIP-1α, MIP-1β, RANTES, TNF-α and GRO-α. Using inhibitory peptides against TLR adapter proteins, FM secretion of MIP-1β and RANTES in response to Poly(I:C) was MyD88 dependent; MIP-1α secretion was dependent on MyD88 and TRIF; and TNF-α production was independent of MyD88 and TRIF. Viral ssRNA-induced FM secretion of IL-1β, IL-2, IL-6, G-CSF, MIP-1α, RANTES and GRO-α was dependent on MyD88 and TRIF; MIP-1β was dependent upon TRIF, but not MyD88; and TNF-α and MCP-1 secretion was dependent on neither. Poly(I:C), but not ssRNA, induced an FM antiviral response by up-regulating the expression of IFNβ, myxovirus-resistance A, 2',5'-oligoadenylate synthetase and apolipoprotein B mRNA-editing enzyme-catalytic polypeptide-like 3G. These findings demonstrate that human FMs respond to two viral signatures by generating distinct inflammatory cytokine/chemokine profiles and antiviral responses through different mechanisms.

Viral infection, inflammation and schizophrenia

Schizophrenia is a severe neurodevelopmental disorder with genetic and environmental etiologies. Prenatal viral/bacterial infections and inflammation play major roles in the genesis of schizophrenia. In this review, we describe a viral model of schizophrenia tested in mice whereby the offspring of mice prenatally infected with influenza at E7, E9, E16, and E18 show significant gene, protein, and brain structural abnormalities postnatally. Similarly, we describe data on rodents exposed to bacterial infection or injected with a synthetic viral mimic (PolyI:C) also demonstrating brain structural and behavioral abnormalities. Moreover, human serologic data has been indispensible in supporting the viral theory of schizophrenia. Individuals born seropositive for bacterial and viral agents are at a significantly elevated risk of developing schizophrenia. While the specific mechanisms of prenatal viral/bacterial infections and brain disorder are unclear, recent findings suggest that the maternal inflammatory response may be associated with fetal brain injury. Preventive and therapeutic treatment options are also proposed. This review presents data related to epidemiology, human serology, and experimental animal models which support the viral model of schizophrenia.

Possible roles of proinflammatory and chemoattractive cytokines produced by human fetal membrane cells in the pathology of adverse pregnancy outcomes associated with influenza virus infection

Pregnant women are at an increased risk of influenza-associated adverse outcomes, such as premature delivery, based on data from the latest pandemic with a novel influenza A (H1N1) virus in 2009-2010. It has been suggested that the transplacental transmission of influenza viruses is rarely detected in humans. A series of our study has demonstrated that influenza virus infection induced apoptosis in primary cultured human fetal membrane chorion cells, from which a factor with monocyte differentiation-inducing (MDI) activity was secreted. Proinflammatory cytokines, such as interleukin (IL)-6, tumor necrosis factor (TNF)-α, and interferon (IFN)-β, were identified as a member of the MDI factor. Influenza virus infection induced the mRNA expression of not only the proinflammatory cytokines but also chemoattractive cytokines, such as monocyte chemoattractant protein (MCP)-1, regulated on activation, normal T-cell expressed and secreted (RANTES), macrophage inflammatory protein (MIP)-1β, IL-8, growth-regulated oncogene (GRO)-α, GRO-β, epithelial cell-derived neutrophil-activating protein (ENA)-78, and interferon inducible protein (IP)-10 in cultured chorion cells. These cytokines are postulated to associate with human parturition. This paper, therefore, reviews (1) lessons from pandemic H1N1 2009 in pregnancy, (2) production of proinflammatory and chemoattractive cytokines by human fetal membranes and their functions in gestational tissues, and (3) possible roles of cytokines produced by human fetal membranes in the pathology of adverse pregnancy outcomes associated with influenza virus infection.

Viruses and other infections in stillbirth: what is the evidence and what should we be doing?

In Australia, as in other developed countries, approximately 40-50% of stillbirths are of unknown aetiology. Emerging evidence suggests stillbirths are often multifactorial. The absence of a known cause leads to uncertainty regarding the risk of recurrence, which can cause extreme anguish for parents that may manifest as guilt, anger or bewilderment. Further, clinical endeavours to prevent recurrences in future pregnancies are impaired by lack of a defined aetiology. Therefore, efforts to provide an aetiological diagnosis of stillbirth impact upon all aspects of care of the mother, and inform many parts of clinical decision making. Despite the magnitude of the problem, that is 7 stillbirths per 1000 births in Australia, diagnostic efforts to discover viral aetiologies are often minimal. Viruses and other difficult to culture organisms have been postulated as the aetiology of a number of obstetric and paediatric conditions of unknown cause, including stillbirth. Reasons forwarded for testing stillbirth cases for infectious agents are non-medical factors, including addressing all parents' need for diagnostic closure, identifying infectious agents as a sporadic cause of stillbirth to reassure parents and clinicians regarding risk for future pregnancies, and to reduce unnecessary testing. It is clear that viral agents including rubella, human cytomegalovirus (CMV), parvovirus B19, herpes simplex virus (HSV), lymphocytic choriomeningitis virus (LCMV), and varicella zoster virus (VZV) may cause intrauterine deaths. Evidence for many other agents is that minimal or asymptomatic infections also occur, so improved markers of adverse outcomes are needed. The role of other viruses and difficult-to-culture organisms in stillbirth is uncertain, and needs more research. However, testing stillborn babies for some viral agents remains a useful adjunct to histopathological and other examinations at autopsy. Modern molecular techniques such as multiplex PCR, allow searches for multiple agents. Now that such testing is available, it is important to assess the clinical usefulness of such testing.

Current status of monocyte differentiation-inducing (MDI) factors derived from human fetal membrane chorion cells undergoing apoptosis after influenza virus infection

Influenza virus infection induces apoptosis and the expression of a set of pro-inflammatory cytokine genes, such as interleukin (IL)-6, tumor necrosis factor (TNF)-alpha, interferon (IFN)-beta and IFN-gamma, in cultured human fetal membrane chorion cells. Monocyte differentiation-inducing (MDI) activity in culture supernatants is simultaneously increased by the virus infection. The MDI activity is predominantly influenced by IL-6 molecule in culture supernatants, and partly by TNF-alpha and IFN-beta, but not IFN-gamma, molecules. The MDI factors are able to induce the mRNA expression of macrophage class A scavenger receptor (SR-A), which is one of adhesion and apoptotic cell-recognizing molecules, and gp91(phox), which is a catalytic subunit of reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase enzyme complex, on monocytic cells. As a result, monocytes are initiated to differentiate into well-matured macrophages capable of adhering and producing superoxide through NADPH oxidase. The matured macrophages, obtained from human monocytic leukemia THP-1 cells by the treatment with MDI factors, phagocytose apoptotic chorion cell debris resulting from the virus infection. Subsequent to phagocytosis, an abrupt increase of superoxide production by macrophages may occur. In this article, we summarize recent knowledge about the MDI factors derived from human fetal membrane chorion cells undergoing apoptosis after influenza virus infection, and discuss their possible pathological roles during pregnancy.

Inflammation of choriodecidua induces tumor necrosis factor alpha-mediated apoptosis of human myometrial cells

The present study investigated the ability of human choriodecidua to induce myometrial cell apoptosis through the secretion of tumor necrosis factor alpha (TNF). The secretion of TNF was evaluated in the culture supernatants of amnion and choriodecidua explants that were exposed to the bacterial endotoxin lipopolysaccharide (LPS) to mimic inflammation. The choriodecidua explants produced more TNF than the amnion explants in response to LPS stimulation, despite the fact that the choriodecidua had lower levels of TLR4 expression. Moreover, conditioned medium obtained from LPS-treated choriodecidua explants, but not that from amnion explants, decreased the number of viable cultured myometrial cells and induced cell apoptosis by inducing the overexpression of the proapoptotic protein BAX and by decreasing the expression of the anti-apoptotic protein BCL2. Neutralization of TNF in the choriodecidua-conditioned medium reversed this effect. Exogenous TNF mimicked LPS-treated choriodecidua-conditioned medium in that it induced myometrial cell apoptosis, reduced BCL2 expression, and increased BAX expression. Using neutralizing antibodies against both subtypes of TNF receptors, we found that only TNFRSF1A participates in TNF-induced myometrial cell apoptosis. Our in vitro model of LPS-induced inflammation of human fetal membrane explants suggests a mechanism by which TNF secreted by choriodecidua governs human myometrial cell apoptosis at the end of pregnancy. These data support the hypothesis that TNF participates in the complex network of signaling processes associated with uterine involution.

Effects of Mitogen-Activated Protein Kinase Inhibitors on Tumor Necrosis Factor-α Gene Expression and Apoptosis Induction in Cultured Human Fetal Membrane Chorion Cells Infected with Influenza Virus

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.

Flow-injection immuno-bioassay for interleukin-6 in humans based on gold nanoparticles modified screen-printed graphite electrodes

A flow-injection electrochemical immunoassay system based on a disposable immunosensor for the determination of interleukin-6 (IL-6) was proposed. The immunosensor was prepared by entrapping horseradish peroxidase (HRP)-labeled IL-6 antibody into gold nanoparticles-modified composite membrane at a screen-printed graphite electrode. With a non-competitive immunoassay format, the immunosensor was inserted in the flow system with an injection of sample, and the injected sample containing IL-6 antigen was produced transparent immunoaffinity reaction with the immobilized HRP-labeled IL-6 antibody. The formed antigen-antibody complex inhibited partly the active center of HRP, and decreased the immobilized HRP to H2O2 reduction. The performance and factors influencing the performance of the immunosensor were investigated. Under optimal conditions, the current change obtained from the labeled HRP relative to thionine-H2O2 system was proportional to the IL-6 concentration in the range of 5-100 ng L(-1) with a detection limit of 1.0 ng L(-1) (at 3delta). The flow-injection immunoassay system could automatically control the incubation, washing and measurement steps with acceptable reproducibility and good stability. Moreover, the proposed immunosensors were used to analyze IL-6 in human serum specimens. Analytical results of clinical samples show the developed immunoassay has a promising alternative approach for detecting IL-6 in the clinical diagnosis.

Synthesis of complement proteins in the human chorion is differentially regulated by cytokines

The aim of the current paper was to determine the chorion's contribution to complement synthesis in the placenta and its regulation by cytokines. Biosynthetic labeling followed by immunoprecipitation with polyclonal antibodies was performed in chorionic tissue and chorion-derived cells. Eight complement proteins, factor B, C3, C1r, C1s, C1 inhibitor, factor H, C4 and C2 were detected in chorionic tissue and were secreted extracellularly. In chorion-derived cells, IL-1beta stimulated factor B synthesis but had no effect on C1r, C1 inhibitor, C1s, factor H and C4. TNFalpha had no stimulative effect on any of the complement proteins tested. In contrast, both IL-1beta and TNFalpha highly induced IL-6 secretion in chorion-derived cells, demonstrating the overall responsiveness of these cells to these stimuli. Interestingly, IFN-gamma increased the synthesis of C1s, C1r, C1 inhibitor, C4 and factor H in chorion-derived cells. The fact that the latter two complement proteins have opposing effects on immune activation of the complement cascade demonstrates the complex balance required to both maintain an ability to ward off infections but simultaneously suppress the immune response to enable tolerance of the allograft fetus.

Characterization of monocyte differentiation-inducing (MDI) factors derived from human fetal membrane chorion cells undergoing apoptosis after influenza virus infection

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.