MICA: The role of placental infection in adverse pregnancy outcome.

The context for this study is that there are >5 million births in the EU and >4 million births in the USA and severe adverse outcome of pregnancy is relatively common. For example, in the UK alone, >4000 infants are stillborn per year. The majority of adverse outcomes occur to women who lack known risk factors. Poor placental function is thought to be responsible for the majority of stillbirths (the placenta is the "afterbirth" and is critically important for normal pregnancy). The complications which lead to stillbirth are also associated with infant mortality, disability and, through a poor prenatal environment, ill health in later life. However, the underlying cause of placental dysfunction leading to these complications remains obscure. Infection is clearly one of the major possible explanations when considering possible causes of dysfunction of an organ. Multiple studies have reported high rates of placental inflammation in pregnancies with adverse outcome. Others have reported associations between the presence of antibodies to infectious agents in the mother's blood during pregnancy and the risk of outcomes such as pre-eclampsia (high blood pressure and abnormal kidney function during pregnancy). Others have shown that infection of placental cells in culture with certain bacteria or viruses impairs their function. However, the quality of the evidence around both placental inflammation and placental infection is generally poor. Furthermore, recent developments in the analysis of genetic material have generated powerful new tools to identify the presence of infectious agents in tissue and these have not previously been applied to studying the possible role of placental infection in causing pre-eclampsia and poor fetal growth.

We have been conducting a study since January 2008 (funded by the NIHR Cambridge Comprehensive Biomedical Research Centre). We have recruited women having first pregnancies at the time of their first scan. We obtain blood samples at around 12, 20, 28 and 36 weeks of pregnancy. We also obtain samples of the placenta following birth. We perform extra research scans so that we have detailed information on both the women experiencing complications and the controls with whom they will be compared. By the start of this project, we will have data and samples from more than 4,000 women who have completed the study and this provides a unique and powerful resource to identify whether infection of the placenta is a determinant of common pregnancy complications (pre-eclampsia and poor growth of the baby). Our approach is (1) to detect the presence of genetic material (DNA or RNA) for infectious agents in the placenta, (2) to measure markers of infection and inflammation in the stored blood samples, and (3) to determine whether inflammation in the placenta is more common in complicated pregnancies. Critically, we have also enlisted internationally recognised experts (from the renowned Wellcome Trust Sanger Institute) in the technology of detecting infectious agents (bacteria, viruses etc) in tissue samples.

This project could uncover such a role for a currently recognised infectious agent, or it could even identify if these complications are being caused by some currently unrecognised bacterium or virus. Identification of previously unrecognised infectious causes of disease has been critical in medicine in the last 30 years. Recognition of the role of a bacterium (Helicobacter pylori) transformed the management of peptic ulcer disease and recognition of the role of a virus (human papilloma virus) in cervical cancer has led to vaccination as a preventative approach. If the mystery of adverse pregnancy outcome is partly explained by infection, this could lead to similarly dramatic changes in understanding and generate new approaches to improving the health of mothers and babies.

Adverse pregnancy outcome is often ascribed to "placental dysfunction". However, there is limited mechanistic understanding of the underlying cause. Multiple lines of evidence indicate that clinically unrecognized infection of the placenta is a plausible cause of placental inflammation and dysfunction, but definitive evidence is currently lacking. Since January 2008, we have been conducting a prospective cohort study of unselected nulliparous women attending the Rosie Hospital for antenatal care (funded by the Women's Health theme of the NIHR Cambridge Biomedical Research Centre). Women are recruited at the time of their first ultrasound examination. Participation involves obtaining maternal blood (for serum and plasma) at the first scan (typically ~12 weeks) and at 20, 28, and 36 weeks, plus ultrasound examinations at the same intervals. Following delivery, the placenta and membranes are sampled by a trained technician. We have recruited 4,544 women and all sample and data collection will be complete by May 2013. We will have complete blood and scan data from ~4,250 women and placental samples from ~4,000. We will use these samples to test our hypothesis that placental infection is involved in the aetiology of pre-eclampsia and/or fetal growth restriction (cases). We have the following specific aims: 1. To compare the frequency of detection of nucleic acids encoding for infectious agents in the placenta in cases and controls matched for key maternal and obstetric characteristics. 2. To compare (i) the type, appearance and level of immunoglobulins to infectious agents, and (ii) the level of cytokines associated with placental inflammation; in maternal blood at ~12, 20, 28 and 36 weeks gestational age in cases, in comparison with a common control group of randomly selected women from the same prospectively defined cohort. 3. To quantify placental inflammation (by histopathological and stereological assessment) in the same cases and matched controls, above.

The work proposed in this application has the potential to have significant societal and economic impact, affecting both patients and the wider public.

The work could lead to improvements in health and well-being in several ways, with multiple parties, including patients and the public benefiting from the proposed research. One of the most natural responses following a severe adverse outcome of pregnancy is to ask why it happened. Our lack of understanding of the basic mechanisms of major placentally related complications of pregnancy (pre-eclampsia, fetal growth restriction and placental abruption) is intensely frustrating for the families who suffer the consequences, such as stillbirth, or admission of a mother to intensive care. Mechanistic understanding of the underlying cause would be viewed very positively and in itself lead to an improvement in well-being, even if there was not an immediate practical application.

Professor Smith has taken part in two receptions for MPs in Westminster hosted by the Stillbirth and Neonatal Death Society (SANDS) and has also gave evidence to an Inquiry by the National Assembly for Wales on rates of Stillbirth in Wales. A frequent view expressed in both political environments was that the magnitude of research activity in this area was not commensurate with the magnitude of the clinical problem. High-quality research in this area may therefore inform public policy in women's health.

Moreover, if the study is successful in identifying infectious causes of complicated pregnancy, this could improve health directly by leading to new methods of prevention and treatment. It is possible that currently unrecognised infectious agents cause some complications. If so, this could lead to diagnostic (e.g. serological tests), curative (e.g. anti-viral therapy) or preventative (e.g. vaccination) strategies. There are clear past examples where this has been the case. The identification of the role of H. pylori in peptic ulcer disease led both to new diagnostic tests and treatment. The identification of the role of HPV in cervical cancer has led to improved risk stratification of women with abnormal smears (by combining cytology with molecular assessment of the presence of oncogenic strains of the virus) and to a vaccination programme which is expected to have a major impact on the disease.

As well as the personal experience of disease, improvements in these areas could have health economic impacts. Over 800,000 women become pregnant each year in the UK. Given a 1% rate of severe pre-eclampsia, 8,000 pregnant women a year become acutely unwell during pregnancy due to pre-eclampsia, requiring intra-venous magnesium sulphate, with some also requiring expensive medical interventions such as emergency caesarean delivery or admission to intensive care. There are also very substantial costs (both short and long term) related to preterm birth secondary to both pre-eclampsia and fetal growth restriction. Better diagnostic, curative and/or preventative approaches would potentially be self-financing through reduced costs of care, both in the short and long term.

Finally, the project has considerable potential to lead to benefits to the wealth of the UK. Although our industrial partner has a head office in the US, Alere have a very significant UK base. The company was previously called Inverness Medical UK Ltd and maintains a large UK presence. Generation of new IP during this project may be commercially exploitable and is likely to attract research and development investment. This would be beneficial for Cambridge University and, hence, have direct benefits for the UK. However, given Alere's significant UK presence, positive effects of new IP for Alere would also be beneficial for the wider UK economy.