Pre-eclampsia could result from the ejection of the fetus by its mother's immune system, say Australian researchers.
Published in the highly accredited Journal of Immunology, the paper explains for the first time that a small population of immune cells called Regulatory T-cells might play an important role in preventing rejection during normal pregnancy.†
Preeclampsia is a leading cause of complications and even death amongst pregnant women in Australia. It is the country's most common serious medical disorder in pregnancy, affecting 5-10 per cent of expectant mothers. Yet the causes of this illness remain a mystery and apart from delivering the baby, there is no known cure.
This discovery is the result of collaboration between Centenary Institute's Professor Barbara Fazekas de St Groth and University of Sydney Medical School Professor Ralph Nanan.†
Both Professor Nanan and Professor Fazekas hope that this finding will enable doctors to reduce the effects and severity of preeclampsia.† This could lead to improved outcomes for patients like Carley Payne, who developed the condition during her first pregnancy, forcing her to deliver her son Dylan at only 25 weeks.
"I remember being so scared.† I just couldn't think straight.† I had no control over anything and I didn't really know what was going on" said Carley.
"After Dylan was born, he had to stay in the hospital on oxygen and in a humidy crib for three months.† It was two weeks before I even got to hold him.† He almost died twice.† I was worried about Dylan, it was such an emotional time."
Preeclampsia is an illness that only occurs in pregnancy, most commonly arising during the second half of the gestation period. It can cause multiple problems, such as high blood pressure, kidney failure, leakage of protein into the urine, thinning of the blood, liver dysfunction and occasionally, convulsions.
The baby of a preeclamptic mother may grow slower than normal in the womb or suffer a potentially harmful oxygen deficiency. Often the baby has to be delivered prematurely to avoid serious complications which would threaten the life of the baby and the mother.†
In addition, due to healthcare costs and long-term care for disorders linked to premature birth, this condition causes an annual global financial burden estimated to be in the billions of dollars.†††
Professor Nanan and Professor Fazekas studied the Regulatory T-cell levels of pregnant mothers at the time of delivery, and compared them with those of mothers who had preeclampsia.
"What we found, is that in healthy pregnancies, there was an increase in Regulatory T-cell production and a decrease in the production of cells that cause inflammation.† Patients with preeclampsia however did not experience these normal immune adaptations to pregnancy", said Professor Nanan.
Professor Fazekas explains, "Fifty years ago researchers hypothesized that preeclampsia is caused by the immune system's inability to generate proper tolerance to the baby but it has been very difficult to prove.† Our research reinforces the belief preeclampsia is initiated, at least in part, by an immune mediated problem that leads to an increase in inflammation."
"Each person has a set of transplantation antigens that are on all cells and are unique to that person. Normally, the immune system will reject anything that has foreign antigens.† Pregnancy is therefore an interesting phenomenon, because the mother's body normally accepts the fetus even though the baby gets half of its antigens from the father, which would usually register as foreign to the mother's immune system."
"We found that the changes in the balance between Regulatory T-cells and inflammatory T-cells in pregnancy may be crucial in stopping the mother's immune system from rejecting the baby.† In preeclampsia, when these changes do not occur, both the baby and the mother are put at risk."
According to Professor Fazekas, "We still have a long way to go to make preeclampsia a condition of the past, but we have opened up a new way of looking at the illness which could lead to new diagnostics and therapies, meaning healthier mothers and babies."