Sphingosine-1-phosphate and vitamin D as modifiable essential mediators of human placental development

During pregnancy, the placenta forms the physical connection between a mother and her baby. One of its jobs is to transfer nutrients and oxygen from maternal to fetal blood. Blood flow is normally controlled by squeezing or relaxing the elastic walls of blood vessels, so that they become narrower or wider as required. In pregnancy however, the walls of the maternal vessels in the womb are invaded, broken down and rebuilt by placental cells, called trophoblast, to make the vessels constantly wide. This ensures that the placenta is supplied with sufficient blood to provide the developing baby with all the building blocks it needs to grow properly. Evidence from previously published work suggests that the normal invasion of the mother's womb is deficient in pregnancy diseases such as pre-eclampsia and fetal growth restriction. If the blood vessels aren't altered properly, the mother can become seriously ill and the baby can be born too small or too early. There's also a life-long impact on health as infants from such pregnancies have an increased chance of developing obesity, cardiovascular disease or diabetes in adulthood.
Currently, there is no way to correct these defects in placental development. Drug companies shy away from making drugs for use in pregnancy because they are fearful of harming unborn babies with their new products, and want to avoid expensive lawsuits. Instead, they invest in other areas of research, leaving doctors with few alternatives for treating pregnant women. One potential solution to this problem is to exploit compounds, such as hormones, that are naturally synthesized by the body, or to utilize drugs that target relevant pathways but have been developed for other diseases.
In this proposal we plan to investigate how trophoblast invasion and transformation of maternal blood vessels are affected by a lipid known as sphingosine-1-phosphate (S1P). S1P is known to control the movement of cells in other organ systems and animal models, but little is known about its role during early pregnancy. So far, our experiments, using models of the cells at the maternal-fetal interface, suggest that the chemical machinery needed to respond to this lipid is present and that S1P stops the trophoblast from moving. We also have data from pilot studies to suggest that it might be possible to alter the chemical machinery, and therefore prevent the negative effects of S1P, using vitamin D. These preliminary findings are interesting because recent work by other investigators has revealed that the women with pre-eclampsia and / or fetal growth restriction often have low levels of vitamin D.
Here we want to use human and animal tissue to create better models for studying the effect of S1P on trophoblast transformation of blood vessels. We will then test what happens to the breakdown of the vessels from the womb when the activity of S1P is altered by vitamin D and other potential regulators of the S1P machinery; such compounds have been developed as therapies for cancer and neurological disease. If our results are good, we would apply for further funding for a clinical trial to test the drugs in women whose pregnancies are complicated by pre-eclampsia or fetal growth restriction.
Novel approaches to tackling the sub-optimal fetal growth caused by pregnancy disease are desperately needed; not only do fetal growth abnormalities have devastating consequences for individual families, they contribute to the significant societal and economic burden associated with obstetric/neonatal care and the management of adult chronic disease.

The development of a functioning placental unit is dependent upon extravillous trophoblast (EVT) invasion and remodelling of maternal blood vessels; failure of this process leads to the pregnancy complications pre-eclampsia (PE) and fetal growth restriction (FGR) and a significant risk of immediate mortality and long term morbidity for both mother and child. The molecular mechanisms responsible for coordinating trophoblast and vascular cell interactions are unknown. However, evidence from other systems suggests a key role for the bioactive lipid, sphingosine-1-phosphate (S1P). Our preliminary data show that S1P inhibits EVT migration via activation of S1P receptor 2 (S1PR2), suggesting that aberrant control of signalling through S1PR2 could contribute to unfavourable trophoblast behaviour; indeed the levels of a known S1PR2 regulator - vitamin D - are perturbed in PE/FGR. Excitingly, we have also found that vitamin D attenuates the S1P/S1PR2 pathway in an EVT cell line.

Here we will to define the role of S1P signalling in directing EVT invasion and vessel transformation and test the potential of novel and repurposed therapeutic interventions as strategies for enhancing vascular remodelling.
Specifically we will use human first trimester placenta and rodent models in ex vivo and in vivo assays of normal and abnormal placentation to test our hypotheses that:
(1) S1P orchestrates EVT invasion and spiral artery transformation in normal placental development;
(2) Low vitamin D levels favour inappropriate S1P signalling contributing to the shallow placentation and vascular abnormalities associated with PE/FGR;
(3) Correcting S1P signalling by direct (e.g. S1PR agonist/antagonists) or indirect (e.g. vitamin D supplementation) intervention strategies will improve placental development and outcomes in PE/FGR.

The pregnancy complications pre-eclampsia (PE) and fetal growth restriction (FGR) have life-long health consequences for both mother and child that can lead to a considerable social and financial burden for society as well as affected families. Our research will lead to an intervention to prevent these common pregnancy diseases. Once developed, the intervention will be of immediate benefit to (i) women and infants affected by PE/FGR and (ii) the healthcare professionals who care for them. Ultimately, however, preventing in utero programming of disease will improve population health, well-being and prosperity throughout the UK.

Women, unborn children and infants will benefit from this research because PE and FGR complicate up to 10% of human pregnancies and are responsible for massive maternal and fetal morbidity. In the UK, PE causes the deaths of 3-5 women and 600 babies per annum; FGR is associated with 40% of the 4000 stillbirths that occur each year. Furthermore, there is overwhelming evidence to suggest that lifelong health is programmed in utero and being born growth restricted or prematurely greatly increases the risk of adult cardiovascular disease and diabetes. In turn, poor health in adulthood will affect the in utero development and wellbeing of subsequent offspring, creating a cycle of ill-health for subsequent generations. Thus poor in utero health has health effects and economic consequences for the entire the 21st century.

There is no curative treatment for PE or FGR and the only therapy is premature delivery. As a result PE-affected pregnancies account for 20% of the occupancy of intensive care baby cots and in combination with the enhanced neonatal requirements of FGR infants, the NHS spends in excess of £420M annually. The cost of providing care for people with chronic diseases, including diabetes, and cardiovascular disease, is in excess of £70 billion / year. Thus the health, social and economic burdens of PE and FGR are substantial and will only be reduced by the introduction of new effective treatments. Our work aims to identify mechanisms for enhancing vascular remodelling in order to develop safe, low cost pharmaceutical interventions for preventing the impaired arterial remodelling that causes these pregnancy disorders. Consequently, in addition to having an impact on maternal and fetal mortality and morbidity, our findings promise to reduce costs associated with caring for sick babies as well as offering novel and affordable treatments for pregnant women with these rather common problems. Thus benefits will flow to clinicians, managers and commissioners in the NHS and will be of interest to the pharmaceutical industry.

We have well-established mechanisms for informing stakeholders of our research findings. All applicants have honorary NHS appointments, providing opportunities to inform patients and hospital- and community-based clinicians, both regionally and nationally, of our findings. MW and JDA also have joint appointments in the Faculty of Life Sciences enabling communication of emerging data and concepts to colleagues and students in the basic sciences. We will convey our findings to the wider scientific, clinical and lay communities by continuing our policy of publishing in high impact journals, presenting at key National and International meetings and broadcasting in the social media through the Twitter feed and Facebook pages of our Institutes, funding partners and academic Societies. The Universities of Manchester and Birmingham have an effective system for early filing of patents on exploitable IP, and the Manchester Biosciences Incubator has been established to support researchers in organizing and exploiting patentable research. The Maternal and Fetal Health Research Centre hosts the UK's first placenta clinic, which, in conjunction with the Manchester Academic Health Sciences Centre, will facilitate movement of our discoveries into new treatments.