Influenza pathogenicity during pregnancy in women and animal models

Pregnant women are at the highest risk to develop severe and even fatal influenza. The high vulnerability of women against influenza A virus infections during pregnancy was repeatedly highlighted during influenza pandemics including the pandemic of this century. In 2009, mortality rates were particularly high among otherwise healthy pregnant women. However, our current understanding of the molecular mechanisms involved in severe disease development during pregnancy is still very limited. In this review, we summarize the knowledge on the clinical observations in influenza A virus-infected pregnant women. In addition, knowledge obtained from few existing experimental infections in pregnant animal models is discussed. Since clinical data do not provide in-depth information on the pathogenesis of severe influenza during pregnancy, adequate animal models are urgently required that mimic clinical findings. Studies in pregnant animal models will allow the dissection of involved molecular disease pathways that are key to improve patient management and care.

An international network (PlaNet) to evaluate a human placental testing platform for chemicals safety testing in pregnancy

The human placenta is a critical life-support system that nourishes and protects a rapidly growing fetus; a unique organ, species specific in structure and function. We consider the pressing challenge of providing additional advice on the safety of prescription medicines and environmental exposures in pregnancy and how ex vivo and in vitro human placental models might be advanced to reproducible human placental test systems (HPTSs), refining a weight of evidence to the guidance given around compound risk assessment during pregnancy. The placental pharmacokinetics of xenobiotic transfer, dysregulated placental function in pregnancy-related pathologies and influx/efflux transporter polymorphisms are a few caveats that could be addressed by HPTSs, not the specific focus of current mammalian reproductive toxicology systems. An international consortium, "PlaNet", will bridge academia, industry and regulators to consider screen ability and standardisation issues surrounding these models, with proven reproducibility for introduction into industrial and clinical practice.

MicroRNA-141 is upregulated in preeclamptic placentae and regulates trophoblast invasion and intercellular communication

Preeclampsia (PE) is one of the leading causes of maternal and perinatal morbidity and mortality worldwide. Abnormal expression of microRNAs (miRNAs) occurs in several pregnancy diseases including PE. Placental trophoblast cells express a specific set of miRNAs which changes during pregnancy. These miRNAs can be released within extracellular vesicles (EVs) and mediate intercellular communication. miR-141 is a pregnancy-related miRNA which is expressed by trophoblast cells at increased levels in maternal plasma in the third trimester. We hypothesize that miR-141 is abnormally expressed in PE placentae, controls trophoblast, and immune cell functions and is involved in the intercellular communication between fetal trophoblast and maternal immune cells. Expression of miR-141 was analyzed by quantitative real-time PCR (qPCR) in normal and preeclamptic placentae and in 2 different trophoblastic cell lines, JEG-3 and HTR-8/SVneo. Changes in JEG-3 and HTR-8/SVneo cell proliferation and invasion were investigated after miR-141 inhibition and overexpression by MTS-, BrdU-, and Matrigel assays. EVs from miR-141 transfected cells were isolated from supernatants and characterized by NanoSight analysis and qPCR. Proliferation of Jurkat T cells and invasion of HTR-8/SVneo cells were investigated after treatment with EVs containing different miR-141 levels. miR-141 expression was higher in placentae from PE patients compared with those from normal pregnancies. miR-141 inhibition in trophoblastic cells resulted in decreased cell viability and reduced invasion capability. After transfection with miR-141-mimic, trophoblastic cells secreted EVs with increased miR-141 content. These vesicles did not exert effects on trophoblastic cell invasion but reduced Jurkat T cell proliferation. In conclusion, miR-141 regulates major functions of trophoblastic and immune cells. Trophoblast cells release EVs whose miRNA content can be modified by transfection of origin cells. Furthermore, elevated levels of miR-141 can be transferred from trophoblast to immune cells by release and internalization of EVs suggesting their role in the immune regulation of normal and pathologic pregnancies.