Pregnancy health centre

New insight into pre-eclampsia

6^th October 2010 - UK scientists have discovered a mechanism which raises blood pressure in pre-eclampsia - a serious complication of pregnancy.

Researchers hope the discovery will lead to new ways to treat pre-eclampsia and hypertension (high blood pressure) in general.

Pre-eclampsia

NHS figures show that milder forms of pre-eclampsia can affect one in ten first pregnancies. More severe pre-eclampsia can affect between 1-2% of pregnancies. Pre-eclampsia usually occurs during the second half of pregnancy, from around week 20, or immediately after delivery.

Pre-eclampsia complications cause the deaths of around six women and several hundred babies every year in the UK.

New research

It has taken 20 years of research for scientists from the Universities of Cambridge and Nottingham to understand the first step in the main process that controls blood pressure.  

Blood pressure is controlled by hormones called angiotensins, which cause the blood vessels to narrow.  These hormones are released by the protein angiotensinogen, but until now, scientists didn’t understand how this happens.

The researchers used a super powerful X-ray machine called a synchrotron to look at the structure of angiotensinogen. The beams are around 100 billion times brighter than a standard hospital X-ray machine and 10 billion times brighter than the sun.

Their results revealed that the protein is oxidised and changes shape to permit ready access to angiotensinogen by an enzyme, renin.  Renin cuts off the tail of the protein to release the hormone angiotensin, which then raises blood pressure.

New leads

The research combined laboratory results from Cambridge and clinic research at Nottingham.

Researchers found the amount of oxidised and more active angiotensinogen was increased in women with pre-eclampsia.

Current blood pressure medications such as ACE inhibitors work on the later stages of the process that controls blood pressure.  Newer treatments may be able to make a difference earlier in that process.

Professor Fiona Broughton Pipkin from the Department of Obstetrics and Gynaecology, University of Nottingham, says in a statement: “We sent coded samples to Cambridge and were thrilled when we broke the code to find that the results fitted our prediction beautifully. They also fit with the changes in the placenta in pre-eclampsia. This is an absolutely novel approach, which is providing new insights into what goes wrong in pre-eclampsia.”

Dr Aiwu Zhou from the University of Cambridge says in a statement: “Although we primarily focused on pre-eclampsia, the research also opens new leads for future research into the causes of hypertension in general.”

Reaction

The British Heart Foundation (BHF) helped fund the research.

BHF medical director, Professor Peter Weissberg, says in a news release:  “This research is of the highest quality and offers real hope for developing strategies to prevent or treat this dangerous condition by targeting the process that these scientists have identified. And of course, although the researchers only looked at pre-eclampsia in this study, similar strategies may be useful for those people with high blood pressure that is not effectively controlled by current medicines.”

The research is published in the journal Nature.

Read more about pre-eclampsia here.