Differential mRNA expression of inflammatory cytokines in cultured human fetal membrane cells responding to influenza virus infection

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.

Crescentic Glomerulonephritis: Pathogenesis and Therapeutic Potential of Human Amniotic Stem Cells

Chronic kidney disease (CKD) leads to significant morbidity and mortality worldwide. Glomerulonephritis (GN) is the second leading cause of CKD resulting in end stage renal failure. The most severe and rapidly progressive type of GN is characterized by glomerular crescent formation. The current therapies for crescentic GN, which consist of broad immunosuppressive drugs, are partially effective, non-specific, toxic and cause many serious side effects including infections, cancer, and cardiovascular problems. Therefore, new and safer therapies are needed. Human amniotic epithelial cells (hAECs) are a type of stem cell which are isolated from the placenta after birth. They represent an attractive and novel therapeutic option for the treatment of various inflammatory conditions owing to their unique and selective immunosuppressive ability, as well as their excellent safety profile and clinical applicability. In this review, we will discuss the immunopathogenesis of crescentic GN, issues with currently available treatments and how hAECs offer potential to become a new and harmless treatment option for this condition.

Pregnancy and pandemics: Interaction of viral surface proteins and placenta cells

Throughout history, pandemics of infectious diseases caused by emerging viruses have spread worldwide. Evidence from previous outbreaks demonstrated that pregnant women are at high risk of contracting the diseases and suffering from adverse outcomes. However, while some viruses can cause major health complications for the mother and her fetus, others do not appear to affect pregnancy. Viral surface proteins bind to specific receptors on the cellular membrane of host cells and begin therewith the infection process. During pregnancy, the molecular features of these proteins may determine specific target cells in the placenta, which may explain the different outcomes. In this review, we display information on Variola, Influenza, Zika and Corona viruses focused on their surface proteins, effects on pregnancy, and possible target placental cells. This will contribute to understanding viral entry during pregnancy, as well as to develop strategies to decrease the incidence of obstetrical problems in current and future infections.

Emerging Cellular Therapies for Anti-myeloperoxidase Vasculitis and Other Autoimmune Diseases

Anti-myeloperoxidase vasculitis (MPO-AAV) is a life-threatening autoimmune disease which causes severe inflammation of small blood vessels, mainly in the kidney. As for many other autoimmune diseases, current treatments, which consist of general immunosuppressants, are partially effective, toxic and broadly immunosuppressive, causing significant and serious adverse effects in many patients. Therefore, there is an urgent need for more targeted and less harmful therapies. Tolerogenic dendritic cells, regulatory T cells and stem cells have emerged as attractive, new and safer options for the treatment for various autoimmune diseases due to their unique and selective immunosuppressive capacity. In this review, we will discuss how these cellular therapies offer potential to become novel and safer treatments for MPO-AAV.

Maternal Influenza A Virus Infection Restricts Fetal and Placental Growth and Adversely Affects the Fetal Thymic Transcriptome

Maternal influenza A viral infections in humans are associated with low birth weight, increased risk of pre-term birth, stillbirth and congenital defects. To examine the effect of maternal influenza virus infection on placental and fetal growth, pregnant C57BL/6 mice were inoculated intranasally with influenza A virus A/CA/07/2009 pandemic H1N1 or phosphate-buffered saline (PBS) at E3.5, E7.5 or E12.5, and the placentae and fetuses collected and weighed at E18.5. Fetal thymuses were pooled from each litter. Placentae were examined histologically, stained by immunohistochemistry (IHC) for CD34 (hematopoietic progenitor cell antigen) and vascular channels quantified. RNA from E7.5 and E12.5 placentae and E7.5 fetal thymuses was subjected to RNA sequencing and pathway analysis. Placental weights were decreased in litters inoculated with influenza at E3.5 and E7.5. Placentae from E7.5 and E12.5 inoculated litters exhibited decreased labyrinth development and the transmembrane protein 150A gene was upregulated in E7.5 placentae. Fetal weights were decreased in litters inoculated at E7.5 and E12.5 compared to controls. RNA sequencing of E7.5 thymuses indicated that 957 genes were downregulated ≥2-fold including Mal, which is associated with Toll-like receptor signaling and T cell differentiation. There were 28 upregulated genes. It is concluded that maternal influenza A virus infection impairs fetal thymic gene expression as well as restricting placental and fetal growth.

Pregnancy Downregulates Plasmablast Metabolic Gene Expression Following Influenza Without Altering Long-Term Antibody Function

While the majority of influenza-infected individuals show no or mild symptomatology, pregnant women are at higher risk of complications and infection-associated mortality. Although enhanced lung pathology and dysregulated hormones are thought to underlie adverse pregnancy outcomes following influenza infection, how pregnancy confounds long-term maternal anti-influenza immunity remains to be elucidated. Previously, we linked seasonal influenza infection to clinical observations of adverse pregnancy outcomes, enhanced lung and placental histopathology, and reduced control of viral replication in lungs of infected pregnant mothers. Here, we expand on this work and demonstrate that lower infectious doses of the pandemic A/California/07/2009 influenza virus generated adverse gestational outcomes similar to higher doses of seasonal viruses. Mice infected during pregnancy demonstrated lower hemagglutination inhibition and neutralizing antibody titers than non-pregnant animals until 63 days post infection. These differences in humoral immunity suggest that pregnancy impacts antibody maturation mechanisms without alterations to B cell frequency or antibody secretion. This is further supported by transcriptional analysis of plasmablasts, which demonstrate downregulated B cell metabolism and post-translational modification systems only among pregnant animals. In sum, these findings corroborate a link between adverse pregnancy outcomes and severe pathology observed during pandemic influenza infection. Furthermore, our data propose that pregnancy directly confounds humoral responses following influenza infection which resolves post-partem. Additional studies are required to specify the involvement of plasmablast metabolism with early humoral immunity abnormalities to best guide vaccination strategies and improve our understanding of the immunological consequences of pregnancy.

Impact of influenza virus during pregnancy: from disease severity to vaccine efficacy

Pregnant women are among the individuals at the highest risk for severe influenza virus infection. Infection of the mother during pregnancy increases the probability of adverse fetal outcomes such as small for gestational age, preterm birth and fetal death. Animal models of syngeneic and allogeneic mating can recapitulate the increased disease severity observed in pregnant women and are used to define the mechanism(s) of that increased severity. This review focuses on influenza A virus pathogenesis, the unique immunological landscape during pregnancy, the impact of maternal influenza virus infection on the fetus and the immune responses at the maternal–fetal interface. Finally, we summarize the importance of immunization and antiviral treatment in this population and highlight issues that warrant further investigation.

Viral infection dampens human fetal membrane type I interferon responses triggered by bacterial LPS

The maternal-fetal interface possesses innate immune strategies to protect against infections. We previously reported that prior viral infection of human fetal membranes (FMs) in vitro and mouse FMs in vivo sensitized the tissue to low dose bacterial LPS leading to augmented inflammation. The objective of this study was to examine FM production of type I interferons (IFNs) and IFN-stimulated genes (ISGs) in the context of this polymicrobial model. Human FM explants and pregnant C57BL/6 mice were treated with or without low dose LPS following exposure to media or the γ-herpes virus, MHV-68. FM RNA was analyzed by qRT-PCR for type I IFNs, ISGs, upstream signaling, and MHV-68 open reading frames (ORFs). Pre-exposure to MHV-68 followed by LPS treatment inhibited the ability of LPS to induce human FM type I IFNs (IFNA, IFNB); ISGs (OAS, MxA, APOBEC3G) and upstream signaling mediators (RIG-I, TBK-1). Signaling mediators IRF-3 and IRF-7 were also reduced. In mouse FMs, pre-exposure to MHV-68 followed by LPS treatment reduced the ability of LPS to upregulate Ifna, Ifnb, Mxa, Irf7, and also reduced Irf3. MHV-68 infection of FMs induced ORF45 which targets IRF-7, and this was further augmented in response to a combination of MHV-68 and LPS. Together, these findings indicate that a viral infection blunts FM type I IFN production and signaling in response to LPS leading to a suppressed ISG response. Our studies suggest that a viral infection inhibits this protective FM response by negatively regulating IRF-7 through ORF45, leaving the maternal-fetal interface vulnerable to further viral attack.

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.

Viperin is induced following toll-like receptor 3 (TLR3) ligation and has a virus-responsive function in human trophoblast cells

INTRODUCTION

Viperin, a virus-inducible antiviral protein, has been reported to inhibit the replication of a variety of viruses. However, its expression and function in trophoblast cells remains unclear. Toll-like receptor 3 (TLR3) is a key component of the innate immune system that recognizes viral double-stranded RNA and triggers immune reactions by producing type I interferon. We hypothesized that viperin inhibits the replication of human cytomegalovirus (HCMV) in trophoblast cells.

METHODS

In situ examinations of viperin expression was conducted in the human first-trimester placenta by immunohistochemical staining. Using a human trophoblast cell culture system, we studied the effect of TLR-3 ligation on viperin expression by treating trophoblasts with polyinosinic-polycytidylic acid [Poly (I: C)] (a synthetic double-stranded RNA, which mimics viral RNA). Viperin mRNA and protein expression were evaluated by real-time PCR and Western blot analysis. In a HCMV infected Swan 71 cell model, HCMV immediate early 1 (IE1) protein mRNA expression was evaluated by real-time PCR after viperin RNA interference.

RESULTS

Viperin was localized in trophoblast cells. Poly (I: C) induced viperin expression in a dosage and time-dependent manner. Blocking of TLR3 signaling by neutralizing antibody against IFN-β abolished the stimulation of viperin expression. After HCMV infection, expression of viperin mRNA and protein was unregulated. HCMV IE1 mRNA expression was significantly inhibited by viperin RNA interference.

DISCUSSION

Viperin is a virus-responsive protein that is constitutively expressed in human trophoblast cells. However, contrary to our hypothesis, viperin facilitates HCMV replication post 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.

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.

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.

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.

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.

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

Influenza virus infection during pregnancy is implicated in one of the causes of premature delivery, abortion and stillbirth. Pro-inflammatory cytokines, such as interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha produced by fetal membranes, are postulated to facilitate premature delivery. We investigated the secretion of IL-6 and TNF-alpha from primary cultured human fetal membrane chorion and amnion cells infected with influenza virus at protein and bioactivity levels in order to understand the pathology of premature delivery during influenza virus infection. Concentrations of IL-6 and TNF-alpha proteins were significantly increased in culture supernatants of chorion cells by influenza virus infection. Culture supernatants of the virus-infected chorion cells stimulated the proliferation of IL-6-sensitive 7-TD-1 cells and induced the cytolysis of TNF-alpha-sensitive L929 cells, both activities of which were inhibited by the addition of respective antibody, whereas no such phenomena were observed in amnion cells. The results demonstrated that only chorion cells secreted significant amounts of bioactive IL-6 and TNF-alpha proteins responding to influenza virus infection. The present study suggests a possibility that the secretion of bioactive IL-6 and TNF-alpha proteins from fetal membrane chorion cells is implicated in the pathogenesis of premature delivery during influenza virus infection.

Effect of bacterial virulence on IL-18 expression in the amnion infected with Escherichia coli

PROBLEM

The upregulation of inflammatory substances threatens pregnancy. Interleukin-18 (IL-18) is elevated in women who miscarried. The purpose of this study was to develop a pig model of chorioamnionitis to study the effect of bacterial virulence on IL-18 response in experimentally infected amnion.

METHOD OF STUDY

A total of 20,000 colony-forming units of Escherichia coli (an enteropathogenic O55 strain, EPEC or O86 non-pathogenic strain) were administered into the amniotic cavity of pig fetuses at 70% of gestation for 10 hr. Fetal amniotic fluid samples were analyzed for IL-18 levels by enzyme-linked immunosorbent assay. The expression of IL-18 was studied also by immunohistochemistry on cryostat sections through amniotic membranes and pathological changes were observed by electron microscopy.

RESULTS

Both E. coli strains propagated in amniotic fluids and reached similar counts. Only EPEC, however, caused a significant increase of IL-18 amniotic fluid levels (P < 0.001) and cytokine expression in the amniotic epithelium.

CONCLUSIONS

The levels of IL-18 in infected amniotic fluids correlated with bacterial virulence and pathological changes in the amnion.

Transcriptional analysis of human peripheral blood mononuclear cells after influenza immunization

Influenza A virus is a major cause of morbidity and mortality worldwide. There is a large knowledge base on the immune response to influenza. However, few studies have focused on global gene expression in immune cells after antigenic challenge. A better understanding of the host immune response is required for the development of more efficient means of prevention and treatment of influenza. In this study, global gene expression in peripheral blood mononuclear cells (PBMCs) after influenza immunization was analyzed. The differential gene expression in antigen-stimulated and non-stimulated PBMCs was determined by cDNA microarrays. To determine whether a specific gene profile was present during a proliferative memory cell response to influenza antigens, gene expression in response to PHA was compared with antigen-stimulated PBMCs. PHA induced the upregulation of 201 genes while influenza virus antigen upregulated more than triple that is 630 genes out of 1700 genes analyzed. Both influenza antigen and PHA commonly upregulated 138 genes. Interferon (IFN)-related genes were induced by influenza but not by PHA. The interferon-gamma induced protein precursor 10 (IP-10) was upregulated 27-fold while the interferon-induced 54 kDa protein exhibited a 13-fold increase. The following gene families were also selectively upregulated by influenza antigens: complement ligands and receptors, T cell activation genes, growth factors, genes related to antigen processing and inflammatory responses. With PHA, the genes TNF-R, CTSG, CD3 delta, C8B, CRF1 and CCR2 had higher expression compared with the viral antigen stimulation. Neutrophil defensins alpha-1 and two C-C chemokines, proteins MIP-1-beta and MIP-4, were among the genes upregulated by both PHA and influenza antigens. The results suggest that interferon-induced genes are one of the main transcriptional targets during the immune response to influenza virus.

Predominant contribution of IFN-beta expression to apoptosis induction in human uterine cervical fibroblast cells by influenza-virus infection

We have been investigating an apoptosis induction in human fetal membrane cells by influenza virus (IV) infection and the contribution of apoptosis induction to the viral infection-defense response between a fetus and the maternal body. For studying any role of uterine cells in the anti-viral response, we investigated the molecular mechanism of the apoptotic induction in human uterine cervical fibroblast cell line (HCF) by IV infection. IV type A and B infection induced DNA fragmentation in HCF. In IV-infected HCF, gene mRNA expression levels of interleukine (IL)-1beta, IL-6, tumor necrosis factor (TNF) alpha, Fas ligand, interferon regulatory factor (IRF)-1, interferon (IFN) alpha and IFN beta increased as compared with those in mock treatment cells, and the induction of mRNAs for double stranded RNA dependent protein kinase (PKR), indolamine 2,3-deoxygenase (IDO) and 2'-5' oligoadenylate synthetase (2-5 OAS) were indicated, which had a role for a host defense response induced by IFN-beta. The amount of IFN-beta protein increased by IV-infection, and DNA fragmentation was inhibited with anti-IFN-beta antibody and PKR inhibitor (2-aminopurine). Furthermore, a synthetic double stranded RNA, poly I : C, could induce almost the same phenomena as that induced by virus infection. We conclude that IV-infection induces the apoptosis in HCF cells through the IFN-beta expression regulated by double stranded RNA and IRF-1 induction, and suggest that the IFN-beta induction may be the predominant contribution to the IV infection induced HCF apoptosis.

Influenza virus induction of apoptosis by intrinsic and extrinsic mechanisms

It is now firmly established that apoptosis is an important mechanism of influenza virus-induced cell death both in vivo and in vitro. Data are predominantly from experiments with influenza A virus and in vitro experimental systems. Multiple influenza virus factors have been identified that can activate intrinsic or extrinsic apoptotic induction pathways. Currently there is no evidence for influenza virus directly accessing the apoptosis execution factors. The best-studied influenza virus inducers of apoptosis are dsRNA, NS1, NA, and a newly described gene product PB1-F2. PB1-F2 is the only influenza virus factor to date identified to act intrinsically by localization and interaction with the mitochondrial-dependent apoptotic pathway. Both dsRNA and NA have been shown to act via an extrinsic mechanism involving proapoptotic host-defense molecules: PKR by induction of Fas-Fas ligand and NA by activation of TGF-beta. PKR is capable of controlling several important cell-signaling pathways and therefore may have multiple effects; a predominant one is increased interferon (IFN) production and activity. NS1 has been shown to be both proapoptotic and antiapoptotic. Use of influenza virus NS1 deletion mutants has provided evidence for NS1 interference with apoptosis, IFN induction, and related cell-signaling pathways. Influenza virus also has important exocrine paracrine effects, which are likely mediated via TNF family ligands and oxygen, free radicals capable of inducing apoptosis. Little is known about activation of inhibitors of apoptosis such as inhibitory apoptotic proteins. Whether all these factors always have a role in influenza virus-induced apoptosis is unknown. The kinetics of synthesis of influenza virus factors affecting apoptosis during the replication cycle may be an important aspect of apoptosis induction.

Apoptosis induced by influenza virus-hemagglutinin stimulation may be related to fluctuation of cellular oxidative condition

Primary cultivated amnion epitherial cells prepared from amnion tissue of human fetal membrane (Amnion-cells) were stimulated with influenza virus-hemagglutinin (IV-HA), fractionated from a commercialized IV-HA vaccine by DEAE Sephacel column chromatography. From 72-96 h after stimulation, chromosomal DNA fragmentation and the appearance of in situ TUNEL stained-positive cells were revealed. Amnion-cell DNA fragmentation was inhibited in the presence of glycophorin A or C purified from the human erythrocyte membrane fraction, but not inhibited with free N-acetyl-neuraminic acid. RT-PCR and Western blotting analysis showed that anti-oxidative enzymes were altered with incubation period, accompanied by the expression of the cellular oxidative stress-related caspase cascade. Pre-stimulation of Amnion-cells with hemin, a heme oxygenase-1 inducer, significantly attenuated IV-HA induced DNA fragmentation. It is concluded that IV-HA induces apoptosis in Amnion-cells, and that this apoptotic induction may be facilitated by certain sialoglycoproteins on the cell surface, and is related to changes in the intracellular redox condition.