Cytomegalovirus infection of trophoblast cells elicits an inflammatory response: a possible mechanism of placental dysfunction

Association Between Maternal Cytomegalovirus Seropositivity, Preterm Birth, and Preeclampsia in Two Cohorts From Quebec, Canada: A Mediation Analysis

PROBLEM

Preterm birth and preeclampsia significantly contribute to infant morbidity and mortality, posing critical public health concerns. Viral infections, particularly Cytomegalovirus (CMV), associated with chronic inflammation, may play a role in these adverse pregnancy outcomes. The contribution of CMV to preterm birth and preeclampsia requires further investigation.

METHOD OF STUDY

Data from 6048 pregnant women from two prospective Quebec cohorts, recruited between May 2005 and August 2012, were analyzed. First-trimester CMV serology was the exposure variable. Associations were assessed using multivariable logistic regression adjusted by inverse probability treatment weighting (IPTW) of propensity scores. Mediation analyses estimated the direct effect of maternal CMV serostatus on preterm birth, excluding mediation by preeclampsia.

RESULTS

Preterm birth and preeclampsia proportions were 5.1% (95% CI: 4.6-5.7) and 1.9% (95% CI: 1.6-2.3), respectively. Multivariable logistic regression adjusted by IPTW showed associations between CMV seropositivity and preterm birth (OR 1.20, 95% CI: 1.02-1.41) and CMV seropositivity and preeclampsia (OR 1.41, 95% CI: 1.08-1.84). Mediation analysis indicated that 97% of the total effect of CMV seropositivity on preterm birth is direct, with the remaining 3% mediated by preeclampsia.

CONCLUSIONS

CMV seropositivity appears to be a risk factor for both preterm birth and preeclampsia. The effect of maternal CMV seropositivity on preterm birth is primarily direct, not mediated by preeclampsia. Future studies should explore the impact of preventive measures against CMV infection on the incidence of preterm delivery and preeclampsia.

Association between cytomegalovirus infection and neurological disorders: A systematic review

Cytomegalovirus (CMV) belongs to the Herpesviridae family and is also known as human herpesvirus type 5. It is a common virus that usually doesn't cause any symptoms in healthy individuals. However, once infected, the virus remains in the host's body for life and can reactivate when the host's immune system weakens. This virus has been linked to several neurological disorders, including Alzheimer's disease, Parkinson's disease, Autism spectrum disorder, Huntington's disease (HD), ataxia, Bell's palsy (BP), and brain tumours, which can cause a wide range of symptoms and challenges for those affected. CMV may influence inflammation, contribute to brain tissue damage, and elevate the risk of moderate-to-severe dementia. Multiple studies suggest a potential association between CMV and ataxia in various conditions, including Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, acute cerebellitis, etc. On the other hand, the evidence regarding CMV involvement in BP is conflicting, and also early indications of a link between CMV and HD were challenged by subsequent research disproving CMV's presence. This systematic review aims to comprehensively investigate any link between the pathogenesis of CMV and its potential role in neurological disorders and follows the preferred reporting items for systematic review and meta-analysis checklist. Despite significant research into the potential links between CMV infection and various neurological disorders, the direct cause-effect relationship is not fully understood and several gaps in knowledge persist. Therefore, continued research is necessary to gain a better understanding of the role of CMV in neurological disorders and potential treatment avenues.

Impact of Co-Occurrence of Obesity and SARS-CoV-2 Infection during Pregnancy on Placental Pathologies and Adverse Birth Outcomes: A Systematic Review and Narrative Synthesis

Obesity is a risk factor for severe COVID-19 disease during pregnancy. We hypothesized that the co-occurrence of high maternal body mass index (BMI) and gestational SARS-CoV-2 infection are detrimental to fetoplacental development. We conducted a systematic review following PRISMA/SWiM guidelines and 13 studies were eligible. In the case series studies (n = 7), the most frequent placental lesions reported in SARS-CoV-2(+) pregnancies with high maternal BMI were chronic inflammation (71.4%, 5/7 studies), fetal vascular malperfusion (FVM) (71.4%, 5/7 studies), maternal vascular malperfusion (MVM) (85.7%, 6/7 studies) and fibrinoids (100%, 7/7 studies). In the cohort studies (n = 4), three studies reported higher rates of chronic inflammation, MVM, FVM and fibrinoids in SARS-CoV-2(+) pregnancies with high maternal BMI (72%, n = 107/149; mean BMI of 30 kg/m2) compared to SARS-CoV-2(−) pregnancies with high BMI (7.4%, n = 10/135). In the fourth cohort study, common lesions observed in placentae from SARS-CoV-2(+) pregnancies with high BMI (n = 187 pregnancies; mean BMI of 30 kg/m2) were chronic inflammation (99%, 186/187), MVM (40%, n = 74/187) and FVM (26%, n = 48/187). BMI and SARS-CoV-2 infection had no effect on birth anthropometry. SARS-CoV-2 infection during pregnancy associates with increased prevalence of placental pathologies, and high BMI in these pregnancies could further affect fetoplacental trajectories.

Potential role of viral infections in miscarriage and insights into the underlying molecular mechanisms

Intrauterine viruses can infect the decidua and placenta and cause adverse effects on the fetus during gestation. This review discusses the contribution of various viral infections to miscarriage and the molecular mechanisms by which viruses can cause devastating effects on healthy fetuses and induce miscarriage. Severe acute respiratory syndrome coronavirus 2 as newly emerged coronavirus was considered here, due to the concerns about its role during pregnancy and inducing miscarriage, as well. In this narrative review, an extensive literature search was conducted to find all studies investigating viral infections in miscarriage and their molecular mechanisms published over the past 20 years. The results of various studies investigating the roles of 20 viral infections in miscarriage are presented. Then, the mechanisms of pregnancy loss in viral infections were addressed, including alteration of trophoblast invasion and placental dysfunction, inducing excessive maternal immune response, and inducing apoptosis in the placental tissue. Viruses may cause pregnancy loss through different mechanisms and our knowledge about these mechanisms can be helpful for controlling or preventing viral infections and achieving a successful pregnancy.

Viral Infections During Pregnancy: The Big Challenge Threatening Maternal and Fetal Health

Viral infections during pregnancy are associated with adverse pregnancy outcomes, including maternal and fetal mortality, pregnancy loss, premature labor, and congenital anomalies. Mammalian gestation encounters an immunological paradox wherein the placenta balances the tolerance of an allogeneic fetus with protection against pathogens. Viruses cannot easily transmit from mother to fetus due to physical and immunological barriers at the maternal-fetal interface posing a restricted threat to the fetus and newborns. Despite this, the unknown strategies utilized by certain viruses could weaken the placental barrier to trigger severe maternal and fetal health issues especially through vertical transmission, which was not fully understood until now. In this review, we summarize diverse aspects of the major viral infections relevant to pregnancy, including the characteristics of pathogenesis, related maternal-fetal complications, and the underlying molecular and cellular mechanisms of vertical transmission. We highlight the fundamental signatures of complex placental defense mechanisms, which will prepare us to fight the next emerging and re-emerging infectious disease in the pregnancy population.

Association between Viral Infections and Risk of Autistic Disorder: An Overview

Autism spectrum disorder (ASD) is a neurodevelopmental condition of the central nervous system (CNS) that presents with severe communication problems, impairment of social interactions, and stereotypic behaviours. Emerging studies indicate possible associations between viral infections and neurodegenerative and neurobehavioural conditions including autism. Viral infection during critical periods of early in utero neurodevelopment may lead to increased risk of autism in the offspring. This review is aimed at highlighting the association between viral infections, including viruses similar to COVID-19, and the aetiology of autism. A literature search was conducted using Pubmed, Ovid/Medline, and Google Scholar database. Relevant search terms included "rubella and autism", "cytomegalovirus and autism", "influenza virus and autism", "Zika virus and autism", "COVID-19 and autism". Based on the search terms, a total of 141 articles were obtained and studies on infants or children with congenital or perinatal viral infection and autistic behaviour were evaluated. The possible mechanisms by which viral infections could lead to autism include direct teratogenic effects and indirect effects of inflammation or maternal immune activation on the developing brain. Brain imaging studies have shown that the ensuing immune response from these viral infections could lead to disruption of the development of brain regions and structures. Hence, long-term follow up is necessary for infants whose mothers report an inflammatory event due to viral infection at any time during pregnancy to monitor for signs of autism. Research into the role of viral infection in the development of ASD may be one avenue of improving ASD outcomes in the future. Early screening and diagnosis to detect, and maybe even prevent ASD are essential to reduce the burden of this condition.

Cyclooxygenase 2 as a Marker of Early Pregnancy Loss in Cytomegalovirus Infection

Background. Increased expression of cyclooxygenase 2 in the placenta plays a significant role in the formation of placental disorders in the pathological course of pregnancy. It was shown that a high level of expression of cyclooxygenase 2 leads to excessive synthesis of prostaglandins, which stimulate the contractile activity of the uterine myometrium and trigger the abortion mechanism. An analysis of modern literature has shown a lack of data proving the involvement of cyclooxygenase 2 in the pathogenesis of early miscarriages in cytomegalovirus infection. Objective. To establish the pathogenetic role of cyclooxygenase 2 in early pregnancy in the course of miscarriage during exacerbation of cytomegalovirus infection. Materials and methods. The study included 86 women with a gestational age of 8–12 weeks, of which 46 women with spontaneous abortion (O03) and exacerbation of cytomegalovirus infection (main group) and 40 women with medical abortion (O04) without cytomegalovirus infection (control group). The material for the study was peripheral blood serum, urine, homogenate of the villous chorion of the placental tissue. The content of cyclooxygenase 2, the level of IgM and IgG antibodies to cytomegalovirus, low-type IgG antibodies to cytomegalovirus (avidity index) were analyzed by enzyme-linked immunosorbent assay; the content of arachidonic acid – by capillary gas-liquid chromatography. Results. During the study, women of the main group found an increase in the concentration of arachidonic acid by 59 % (p < 0.001) and the activity of the lipolytic enzyme cyclooxygenase 2 – by 58 % (p < 0.001) in the placenta villous chorion homogenate. Conclusion. With an exacerbation of cytomegalovirus infection in the homogenate of the villous placenta chorion of pregnant women with spontaneous abortion, an increase in the content of arachidonic acid and the level of cyclooxygenase 2 is observed. An increased level of cyclooxygenase 2 indicates the development of pregnancy complications and can be used as a non-specific marker predictor of pregnancy termination during exacerbation of cytosis.

Is it not time for international guidelines to combat congenital cytomegalovirus infection? A review of central nervous system manifestations

Cytomegalovirus (CMV) is the most commonly transmitted virus in utero with a prevalence of up to 1.5%. The infection has potentially debilitating and devastating consequences for the infected fetus, being a leading cause for neurological disability worldwide. Once acquired, it often goes undetected with only an assumed 10% of infected neonates displaying the classic clinical or imaging features. Viral DNA polymerase chain reaction (PCR) of saliva or urine obtained within the first 21 days of life is required to make the diagnosis. As the majority of infected neonates are initially asymptomatic, diagnosis is often delayed. An abnormal routine neonatal hearing test and characteristic antenatal cranial ultrasound imaging findings may raise the suspicion of congenital CMV (cCMV) in the asymptomatic group. Ultimately, the aim is to facilitate early diagnosis and timely treatment. In this article, we highlight diagnostic and treatment challenges of the commonest congenital infection, we present the current available central nervous system imaging severity grading systems, and highlight the need for an internationally agreed diagnostic grading system that can aid treatment decision-making.

Differential Expression of PDGF Receptor-α in Human Placental Trophoblasts Leads to Different Entry Pathways by Human Cytomegalovirus Strains

Human cytomegalovirus (CMV) is the leading non-genetic cause of fetal malformation in developed countries. CMV placental infection is a pre-requisite for materno-fetal transmission of virus, and fetal infection. We investigated the roles of the viral pentameric complex gH/gL/pUL128-pUL131A, and cellular platelet-derived growth factor receptor-α (PDGFRα) for CMV infection in first trimester extravillous-derived (SGHPL-4) and villous-derived (HTR-8/SVneo) trophoblast cells. Infection with four CMV clinical and laboratory strains (Merlin, TB40E, Towne, AD169), and Merlin deletion mutants of UL128-, UL130-, and UL131A-genes, showed a cell type-dependent requirement of the viral pentameric complex for infection of trophoblast cells. The viral pentameric complex was essential for infection of villous trophoblasts, but non-essential for extravillous trophoblasts. Blocking of PDGFRα in extravillous trophoblasts, which naturally express PDGFRα, inhibited entry of pentameric complex-deficient CMV strains, but not the entry of pentameric positive CMV strains. Transient expression of PDGFRα in villous trophoblasts, which are naturally deficient in PDGFRα, promoted the entry of CMV strains lacking gH/gL/pUL128-pUL131A, but had no effect on entry of pentameric positive CMV strains. These results suggest PDGFRα is an important cell receptor for entry of CMV mutant strains lacking gH/gL/pUL128-pUL131A complexes in some placental cells, suggesting these entry pathways could be potential antiviral targets.

Antiviral Inflammation during Early Pregnancy Reduces Placental and Fetal Growth Trajectories

Many viruses are detrimental to pregnancy and negatively affect fetal growth and development. What is not well understood is how virus-induced inflammation impacts fetal-placental growth and developmental trajectories, particularly when inflammation occurs in early pregnancy during nascent placental and embryo development. To address this issue, we simulated a systemic virus exposure in early pregnant rats (gestational day 8.5) by administering the viral dsRNA mimic polyinosinic:polycytidylic acid (PolyI:C). Maternal exposure to PolyI:C induced a potent antiviral response and hypoxia in the early pregnant uterus, containing the primordial placenta and embryo. Maternal PolyI:C exposure was associated with decreased expression of the maternally imprinted genes Mest, Sfrp2, and Dlk1, which encode proteins critical for placental growth. Exposure of pregnant dams to PolyI:C during early pregnancy reduced fetal growth trajectories throughout gestation, concomitant with smaller placentas, and altered placental structure at midgestation. No detectable changes in placental hemodynamics were observed, as determined by ultrasound biomicroscopy. An antiviral response was not evident in rat trophoblast stem (TS) cells following exposure to PolyI:C, or to certain PolyI:C-induced cytokines including IL-6. However, TS cells expressed high levels of type I IFNR subunits (Ifnar1 and Ifnar2) and responded to IFN-⍺ by increasing expression of IFN-stimulated genes and decreasing expression of genes associated with the TS stem state, including Mest IFN-⍺ also impaired the differentiation capacity of TS cells. These results suggest that an antiviral inflammatory response in the conceptus during early pregnancy impacts TS cell developmental potential and causes latent placental development and reduced fetal growth.

Cadmium exposure induces interleukin-6 production via ROS-dependent activation of the ERK1/2 but independent of JNK signaling pathway in human placental JEG-3 trophoblast cells

Maternal exposure to cadmium (Cd) has been associated with preeclampsia (PE), which is a multisystemic disorder characterized by endothelial dysfunction. Elevated interleukin (IL)-6 expression is linked to PE and has been suggested to contribute to maternal endothelial dysfunction. Cd induces IL-6 production in various cell types through different signaling pathways. Thus, this study was designed to investigate the effect of Cd on IL-6 production and the underlying mechanisms in a trophoblast-derived cell line. Cultured JEG-3 trophoblast cells were exposed to non-toxic concentrations of CdCl₂ in the presence or absence of various MAPK inhibitors or N-Acetyl-L-cysteine (NAC). IL-6 was measured by ELISA. Phosphorylation of ERK1/2, JNK, and c-Jun was assessed by Western blotting. Cd exposure induced IL-6 production and increased ERK1/2, JNK, and c-Jun phosphorylation. NAC and the inhibition of ERK1/2 significantly reduced Cd-induced IL-6 production. These data indicate that Cd induces IL-6 production in trophoblast cells through a ROS-dependent activation of ERK1/2.

CD46 facilitates entry and dissemination of human cytomegalovirus

Human cytomegalovirus (CMV) causes a wide array of disease to diverse populations of immune-compromised individuals. Thus, a more comprehensive understanding of how CMV enters numerous host cell types is necessary to further delineate the complex nature of CMV pathogenesis and to develop targeted therapeutics. To that end, we establish a vaccination strategy utilizing membrane vesicles derived from epithelial cells to generate a library of monoclonal antibodies (mAbs) targeting cell surface proteins in their native conformation. A high-throughput inhibition assay is employed to screen these antibodies for their ability to limit infection, and mAbs targeting CD46 are identified. In addition, a significant reduction of viral proliferation in CD46-KO epithelial cells confirms a role for CD46 function in viral dissemination. Further, we demonstrate a CD46-dependent entry pathway of virus infection in trophoblasts, but not in fibroblasts, highlighting the complexity of CMV entry and identifying CD46 as an entry factor in congenital infection.

Placental Cytomegalovirus Infection

In the United States, cytomegalovirus is the most common congenital viral infection and the number 1 cause of nonhereditary sensorineural hearing loss. The vast majority of infants may be asymptomatic, especially if cytomegalovirus is contracted later in the pregnancy, and some symptoms may have a delayed onset. Therefore, it is important for the pathologist to identify the common histologic findings to help confirm the diagnosis so the child can be followed for late sequelae. Histologic examination of the placenta is important in live births and in cases of intrauterine fetal demise. Chronic lymphoplasmacytic villitis and fibrotic, avascular villi are the most common findings. When present, Cowdry A intranuclear and basophilic intracytoplasmic inclusions are characteristic. Immunohistochemistry for cytomegalovirus can highlight these inclusions as well as the associated eosinophilic debris. In addition, polymerase chain reaction or viral culture on placental or fetal samples can be performed for confirmation.

Maternal cytomegalovirus sero-positivity and autism symptoms in children

PROBLEM

Autism spectrum disorder (ASD) is one of the most commonly diagnosed neurodevelopmental disorders in the United States. While ASD can be significantly influenced by genetics, prenatal exposure to maternal infections has also been implicated in conferring risk. Despite this, the effects of several important maternal pathogens, such as cytomegalovirus (CMV) and herpes simplex virus 2 (HSV2), remain unknown.

METHOD OF STUDY

We tested whether maternal CMV and/or HSV2 sero-positivity was associated with ASD symptoms in children. ELISA was used to assay for CMV IgG and HSV2 IgG in serum from the mothers of 82 children whose ASD symptoms were assessed at 3-6 years of age using the Social Responsiveness Scale version 2 (SRS-2).

RESULTS

Associations between maternal viral serostatus and SRS-2 scores were estimated using linear regression with covariate adjustments. The children of mothers sero-positive for CMV, but not for HSV2, had SRS-2 scores 3.6-4.2 points higher, depending on the adjustment model, than sero-negative women, a significant finding, robust to several statistical adjustments.

CONCLUSION

Our results suggest that maternal CMV infections may influence ASD symptoms. These findings are being further evaluated in ongoing prospective studies with larger population samples.

Congenital Cytomegalovirus Infection: Maternal-Child HLA-C, HLA-E, and HLA-G Affect Clinical Outcome

Congenital CMV infection (cCMV) is the most common congenital infection causing permanent long-term impairments (LTI). cCMV immunopathogenesis is largely unknown due to the complex interplay between viral, maternal, placental, and child factors. In this study, a large retrospective nationwide cohort of children with cCMV and their mothers was used. HLA-C, HLA-E, and HLA-G were assessed in 96 mother–child pairs in relation to symptoms at birth and LTI at 6 years of age. The mothers were additionally typed for killer cell immunoglobulin-like receptors. The maternal HLA-G 14 bp deletion/deletion polymorphism was associated with a worse outcome, as the immunomodulation effect of higher protein levels may induce less CMV control, with a direct impact on placenta and fetus. The absence of maternal HLA-C belonging to the C2 group was associated with symptoms at birth, as activating signals on decidual NK may override inhibitory signals, contributing to a placental pro-inflammatory environment. Here, the increased HLA-E*0101 and HLA-C mismatches, which were associated with symptoms at birth, may enhance maternal allo-reactivity to fetal Ags, and cause suboptimal viral clearance. Finally, HLA-C non-inherited maternal antigens (NIMAs) were associated with LTI. The tolerance induced in the fetus toward NIMAs may indirectly induce a suboptimal CMV antiviral response throughout childhood. In light of our findings, the potential role of maternal–child HLA in controlling CMV infection and cCMV-related disease, and the clinical value as predictor for long-term outcome certainly deserve further evaluation.

Risks associated with viral infections during pregnancy

Despite the prevalence of viral infections in the American population, we still have a limited understanding of how they affect pregnancy and fetal development. Viruses can gain access to the decidua and placenta by ascending from the lower reproductive tract or via hematogenous transmission. Viral tropism for the decidua and placenta is then dependent on viral entry receptor expression in these tissues as well as on the maternal immune response to the virus. These factors vary by cell type and gestational age and can be affected by changes to the in utero environment and maternal immunity. Some viruses can directly infect the fetus at specific times during gestation, while some only infect the placenta. Both scenarios can result in severe birth defects or pregnancy loss. Systemic maternal viral infections can also affect the pregnancy, and these can be especially dangerous, because pregnant women suffer higher virus-associated morbidity and mortality than do nonpregnant counterparts. In this Review, we discuss the potential contributions of maternal, placental, and fetal viral infection to pregnancy outcome, fetal development, and maternal well-being.

The role of infection in miscarriage

BACKGROUND

Miscarriage is the spontaneous loss of a pregnancy before 12 weeks (early miscarriage) or from 12 to 24 weeks (late miscarriage) of gestation. Miscarriage occurs in one in five pregnancies and can have considerable physiological and psychological implications for the patient. It is also associated with significant health care costs. There is evidence that potentially preventable infections may account for up to 15% of early miscarriages and up to 66% of late miscarriages. However, the provision of associated screening and management algorithms is inconsistent for newly pregnant women. Here, we review recent population-based studies on infections that have been shown to be associated with miscarriage.

METHODS

Our aim was to examine where the current scientific focus lies with regards to the role of infection in miscarriage. Papers dating from June 2009 with key words 'miscarriage' and 'infection' or 'infections' were identified in PubMed (292 and 327 papers, respectively, on 2 June 2014). Relevant human studies (meta-analyses, case-control studies, cohort studies or case series) were included. Single case reports were excluded. The studies were scored based on the Newcastle - Ottawa Quality Assessment Scale.

RESULTS

The association of systemic infections with malaria, brucellosis, cytomegalovirus and human immunodeficiency virus, dengue fever, influenza virus and of vaginal infection with bacterial vaginosis, with increased risk of miscarriage has been demonstrated. Q fever, adeno-associated virus, Bocavirus, Hepatitis C and Mycoplasma genitalium infections do not appear to affect pregnancy outcome. The effects of Chlamydia trachomatis, Toxoplasma gondii, human papillomavirus, herpes simplex virus, parvovirus B19, Hepatitis B and polyomavirus BK infections remain controversial, as some studies indicate increased miscarriage risk and others show no increased risk. The latest data on rubella and syphilis indicate increased antenatal screening worldwide and a decrease in the frequency of their reported associations with pregnancy failure. Though various pathogens have been associated with miscarriage, the mechanism(s) of infection-induced miscarriage are not yet fully elucidated.

CONCLUSIONS

Further research is required to clarify whether certain infections do increase miscarriage risk and whether screening of newly pregnant women for treatable infections would improve reproductive outcomes.

Human Cytomegalovirus Modulates Expression of Noncanonical Wnt Receptor ROR2 To Alter Trophoblast Migration

Maternal primary cytomegalovirus (CMV) infection, reactivation, or reinfection with a different viral strain may cause fetal injury and adverse pregnancy outcomes. Increasing evidence indicates that fetal injury results not only from direct viral cytopathic damage to the CMV-infected fetus but also from indirect effects through placental infection and dysfunction. CMV alters Wingless (Wnt) signaling, an essential cellular pathway involved in placentation, as evidenced by reduced transcription of canonical Wnt target genes and decreased Wnt3a-induced trophoblast migration. Whether CMV affects the noncanonical Wnt signaling pathway has been unclear. This study demonstrates for the first time that CMV infection inhibits Wnt5a-stimulated migration of human SGHPL-4 trophoblasts and that inhibition of the pathway restores normal migration of CMV-infected cells. Western blot and real-time PCR analyses show increased expression of noncanonical Wnt receptor ROR2 in CMV-infected trophoblasts. Mimicking the CMV-induced ROR2 protein expression via ectopic expression inhibited Wnt5a-induced trophoblast migration and reduced T cell-specific factor (TCF)/lymphoid enhancer-binding factor (LEF)-mediated transcription as measured using luciferase reporter assays. Gene silencing using small interfering RNA (siRNA) duplexes decreased ROR2 transcript and protein levels. In contrast, proliferation of SGHPL-4 trophoblasts, measured by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was not affected. The siRNA-mediated downregulation of ROR2 in trophoblasts rescued CMV-induced reduction in trophoblast migration. These data suggest a mechanism where CMV alters the expression of the Wnt receptor ROR2 to alter Wnt5a-mediated signaling and inhibit trophoblast motility. Inhibition of this mechanism may be a target for therapeutic intervention for CMV-induced placental damage and consequent fetal damage in congenital CMV infections.

IMPORTANCE

Maternal primary cytomegalovirus (CMV) infection, reactivation, or reinfection with a different viral strain may cause fetal injury and adverse pregnancy outcomes. Increasing evidence indicates that fetal injury results not only from direct viral cytopathic damage to the CMV-infected fetus but also from indirect effects through placental infection and placental dysfunction. No effective therapy is currently proven to prevent or treat congenital CMV infection. Understanding the molecular underpinnings of CMV infection of the placenta is essential for therapeutic innovations and vaccine design. CMV alters canonical Wingless (Wnt) signaling, an essential cellular pathway involved in placental development. This study suggests a mechanism in which CMV alters the expression of noncanonical Wnt receptor ROR2 to alter motility of placental cells, which has important implications in the pathogenesis of CMV-induced placental dysfunction. Inhibition of this mechanism may be a target for therapeutic intervention for CMV-induced placental damage and consequent fetal damage in congenital CMV infection.

Stimulatory effects of human cytomegalovirus tegument protein pp71 lead to increased expression of CCL2 (monocyte chemotactic protein-1) during infection

Human cytomegalovirus (CMV) is the most common infectious cause of congenital birth defects in developed countries. Studies of infected amniotic fluid and placentae show CMV infection leads to a pro-inflammatory shift in cytokine profiles with implications for pathogenesis of foetal disease. ELISA, immunofluorescence and real-time-PCR assays were used to investigate CCL2 (monocyte chemotactic protein-1) and TNF-α changes following CMV infection of human fibroblasts, as well as following transient expression of CMV gene products in HeLa cells. Infection of human fibroblasts with CMV AD169 resulted in increased cytoplasmic and extracellular expression of CCL2 during early stages of infection, followed by marked downregulation of the chemokine at late times. Induction of CCL2 was not observed with CMV clinical strain Merlin, consistent with the postulated immune-evasion potential of this genetically intact WT strain. Comparison between live and UV-irradiated virus infections showed that changes in CCL2 levels were a direct response to active CMV replication. There were no significant changes in TNF-α expression during a parallel time-course of CMV infection. In transient transfection assays, overexpression of CMV tegument protein pp71 resulted in intracellular and extracellular upregulation of CCL2 protein. mRNA analysis showed that pp71-induced elevation in CCL2 was mediated through transcriptional upregulation. The data showed that CMV-induced upregulation of CCL2 during early stages of infection was mediated, at least in part, by stimulation of viral pp71, which may contribute to viral pathogenesis through enhanced virus dissemination.

Human cytomegalovirus infection induces leukotriene B4 and 5-lipoxygenase expression in human placentae and umbilical vein endothelial cells

INTRODUCTION

Human cytomegalovirus (HCMV) can cause congenital infection with risk of neurological disability. Maternal-fetal transmission is associated with placental inflammation. 5-lipoxygenase (5-LO) is the key enzyme in the biosynthesis of Leukotrienes (LTs), which are proinflammatory mediators. This study investigated the effect of HCMV infection on 5-LO expression and Leukotriene-B4 (LTB4) induction in human placentae and umbilical vein endothelial cells (HUVEC).

METHODS

Seven placentae from fetuses with congenital HCMV infection and brain damage and six controls were stained with HCMV-immediate-early-antigen (HCMV-IEA) and 5-LO by immunohistochemistry. 5-hydroxyeicosatetraenoic acid (5-HETE) and LTB4 were measured in culture supernatant from ex vivo HCMV-infected placental histocultures by liquid chromatography. In vitro, HCMV infected HUVEC cells were analyzed for 5-LO mRNA and protein expression by real time PCR and immunofluorescence staining.

RESULTS

HCMV-IEA was abundant in all HCMV infected placentae but absent in control placentae. 5-LO expression was higher in endothelial and smooth muscle cells of HCMV-infected placentae, compared to control placentae. HCMV infection induced an up-regulation of LTB4 in ex vivo placental explants with higher levels of LTB4 at 72 h compared to controls (p = 0.002). In vitro, 5-LO transcript and protein expression were significantly induced in HCMV-infected HUVEC, compared to the control cultures (p = 0.036).

CONCLUSION

The presence of HCMV coincided with high 5-LO expression in cells of in vivo HCMV infected placentae. HCMV induced up-regulation of 5-LO in both ex vivo HCMV-infected placental explants and HUVEC. HCMV induced LT-biosynthesis in congenitally infected placentae may have a role in pathogenesis of congenital HCMV disease.

Human cytomegalovirus infection inhibits CXCL12- mediated migration and invasion of human extravillous cytotrophoblasts

Background

During the first trimester of pregnancy, a series of tightly regulated interactions govern the formation of a highly invasive population of fetal-derived extravillous cytotrophoblasts (EVT). Successful pregnancy is dependent on efficient invasion of the uterine wall and maternal spiral arteries by EVT. Dysregulated trophoblast invasion is associated with intrauterine growth restriction, birth defects, spontaneous abortion and preeclampsia. A number of soluble growth factors, cytokines, and chemokines modulate this process, fine-tuning the temporal and spatial aspects of cytotrophoblast invasion. In particular, the CXCL12/CXCR4 axis has been shown to specifically modulate cytotrophoblast differentiation, invasion, and survival throughout early pregnancy. Infection with human cytomegalovirus (HCMV) has been associated with impaired differentiation of cytotrophoblasts down the invasive pathway, specifically dysregulating the response to mitogens including epidermal growth factor (EGF) and hepatocyte growth factor (HGF). In this study, the effect of HCMV infection on the CXCL12-mediated migration and invasion of the EVT cell line SGHPL-4 was investigated.

Results

Infection with HCMV significantly decreased secretion of CXCL12 by SGHPL-4 cells, and induced a striking perinuclear accumulation of the chemokine. HCMV infection significantly increased mRNA and total cell surface expression of the two known receptors for CXCL12: CXCR4 and CXCR7. Functionally, HCMV-infected SGHPL-4 cells were unable to migrate or invade in response to a gradient of soluble CXCL12 in transwell assays.

Conclusions

Collectively, these studies demonstrate that HCMV impairs EVT migration and invasion induced by CXCL12. As HCMV has the ability to inhibit EVT migration and invasion through dysregulation of other relevant signaling pathways, it is likely that the virus affects multiple signaling pathways to impair placentation and contribute to some of the placental defects seen in HCMV-positive pregnancies.

Establishment of a choriocarcinoma model from immortalized normal extravillous trophoblast cells transduced with HRASV12

Gestational choriocarcinoma is a malignant trophoblastic tumor. The development of novel molecular-targeted therapies is needed to reduce the toxicity of current multiagent chemotherapy and to treat successfully the chemoresistant cases. The molecular mechanisms underlying choriocarcinoma tumorigenesis remain uncharacterized, however, and appropriate choriocarcinoma animal models have not yet been developed. In this study, we established a choriocarcinoma model by inoculating mice with induced-choriocarcinoma cell-1 (iC³-1) cells, generated from HTR8/SVneo human trophoblastic cells retrovirally transduced with activated H-RAS (HRASV12). The iC³-1 cells exhibited constitutive activation of the mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) pathways and developed into lethal tumors in all inoculated mice. Histopathological analysis revealed that the tumors consisted of two distinct types of cells, reminiscent of syncytiotrophoblasts and cytotrophoblasts, as seen in the human choriocarcinoma. The tumors expressed HLA-G and cytokeratin (trophoblast markers) and hCG (a choriocarcinoma marker). Comparative analysis of gene expression profiles between iC³-1 cells and parental HTR8/SVneo cells revealed that iC³-1 cells expressed matrix metalloproteinases, epithelial-mesenchymal transition-related genes, and SOX3 at higher levels than parental trophoblastic cells. Administration of SOX3-specific short-hairpin RNA decreased SOX3 expression and attenuated the tumorigenic activity of iC³-1 cells, suggesting that SOX3 overexpression might be critically involved in the pathogenesis of choriocarcinoma. Our murine model represents a potent new tool for studying the pathogenesis and treatment of choriocarcinoma.

Interleukin-8 (CXCL8) stimulates trophoblast cell migration and invasion by increasing levels of matrix metalloproteinase (MMP)2 and MMP9 and integrins alpha5 and beta1

Interleukin-8 (IL8/CXCL8) is present in decidua and trophoblast, which also expresses the IL8 receptors, CXCR1 and CXCR2. IL8 was shown to stimulate trophoblast migration. Matrix metalloproteinase (MMP)2, MMP9, and integrins alpha(5)beta(1) and alpha(1)beta(1) were found to play important roles in trophoblast invasion. We hypothesized that IL8 would increase this cell migration and invasion by HTR-8/SVneo cells through the activity of MMPs and integrins. Isolated first trimester of pregnancy cytotrophoblast (CT) and HTR-8/SVneo cell line were used. Migration was studied by monolayer wounding test, and invasion by Matrigel invasion test. The effects of IL8 on MMPs and integrin subunit expression were determined in HTR-8/SVneo cells by gelatin zymography and western blot respectively. The results that were obtained showed that exogenous IL8 stimulated HTR-8/SVneo cell migration and invasion. MMP2 and MMP9 levels were stimulated to 182% (P<0.01) and 134% (P<0.01) respectively. Integrin alpha(5) expression was increased to 119% (P<0.05) and integrin beta(1) expression to 173% (P<0.001) of the control values. The data that were obtained show for the first time the sensitivity of the HTR-8/SVneo cells, in addition to isolated first trimester CT, to IL8. Exogenous IL8/CXCL8 increased trophoblast cell migration and invasion, which may be partly attributable to stimulation of MMP2 and MMP9 levels and an increase in integrins. HTR-8/SVneo cell viability and proliferation were also increased.

Trophoblast infection with Chlamydia pneumoniae and adverse pregnancy outcomes associated with placental dysfunction

OBJECTIVE

We sought to determine whether Chlamydia pneumoniae impairs invasive trophoblast function and is associated with preeclampsia.

STUDY DESIGN

We conducted cell viability and invasion assays using primary extravillous trophoblast cells isolated from first-trimester placentas. We performed a case-control study to identify C pneumoniae in trophoblast cells dissected by laser capture microscopy from placentas in women with severe preeclampsia and control subjects who delivered at term.

RESULTS

Trophoblast cell viability and invasion through extracellular matrices were decreased after infection with C pneumoniae (both P < .05). C pneumoniae DNA was detected in trophoblast cells in 15/48 cases but only 3/30 controls (odds ratio, 4.1; P = .02). Positive and negative controls yielded expected results.

CONCLUSION

C pneumoniae infection can reduce trophoblast invasion into the uterine wall and is associated with preeclampsia. Further investigation of the mechanisms by which C pneumoniae induces trophoblast dysfunction, and the identification of therapies to prevent adverse outcomes attributed to trophoblast dysfunction, are warranted.

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.

Multidrug resistance proteins affect drug transmission across the placenta

OBJECTIVE

We studied the role of multidrug resistance proteins in regulating transplacental transmission of corticosteroids and protease inhibitors.

STUDY DESIGN

We performed quantitative polymerase chain reaction and FACS analyses to study MDR1 (encodes P-glycoprotein) and MRP-1 expression in extravillous (HTR-8/SVneo) and villous (BeWo) trophoblast cells treated with saquinavir, a multidrug resistance protein substrate. We measured H3-dexamethasone and H3-ritonavir transfer across confluent, syncytialized BeWo cells before and after treatment with agents that inhibit multidrug resistance proteins.

RESULTS

Compared with baseline expression, messenger RNA and protein levels were increased significantly in trophoblast cells after treatment with saquinavir. H3-dexamethasone and H3-ritonavir levels increased in BeWo cells after treatment with anti-P-glycoprotein antibodies or cyclosporine A. Transfer of H3-labeled drugs from the apical (eg, maternal) to basolateral (eg, fetal) side of the syncytialized BeWo cell monolayer was increased significantly when cells were pretreated with anti-P-glycoprotein antibodies.

CONCLUSION

Multidrug resistance proteins regulate drug levels in trophoblast cells and may mediate transmission of therapeutic agents across the placenta.

Placental inflammation and viral infection are implicated in second trimester pregnancy loss

OBJECTIVE

Second trimester pregnancy loss continues to be a poorly understood adverse obstetric outcome. A case control study was performed to determine if: (1) similar to early spontaneous preterm birth, second trimester loss is associated with histologic chorioamnionitis (HCA); and (2) if HCA is present, which organisms may mediate this placental inflammation.

STUDY DESIGN

Cases were patients with a spontaneous second trimester loss. Controls were patients who presented for induction of labor for fetal or maternal indications. Nested polymerase chain reaction (PCR) was performed on placental tissues to detect the presence of viruses and pathogenic and atypical bacteria. Chi-square and Fisher exact test were used to determine if HCA and/or the presence of virus or bacteria were significantly associated with second trimester loss. The associations of interest were adjusted for possible confounders using multivariable logistic regression.

RESULTS

HCA was more prevalent in cases (67%) than controls (16%) (P < .001). Seventy-nine percent (66/84) of cases and 44% (7/16) of controls were positive for any virus (P = .01). The rate of bacterial infection was similar in both cases and controls (P = .35). In multivariable logistic regression models, HCA (odds ratio [OR] 14.58, 2.62-81.15) and the presence of any virus (OR 6.62, 1.56-28.07) were independently associated with second trimester loss.

CONCLUSION

These studies demonstrate that spontaneous second trimester loss is strongly associated with HCA and viral infections.