Menopause news

Estrogen helps protect women from cardiovascular disease by effects on immune system

23 August 2011

For some time it has been known that heart disease in women is uncommon before the menopause, but that the rate increases significantly after the menopause, when estrogen levels are low. Indeed, cardiovascular disease is the commonest cause of death in women after the menopause; an important fact about which there is still a worryingly low level of awareness. Much debate has taken place about the role of estrogen and how it may protect against cardiovascular disease. New research from scientists at Queen Mary University of London sheds more light on the matter and suggests that estrogen could help protect women from cardiovascular disease by effects on the body’s immune system.

The study has shown that estrogen works on white blood cells to stop them from sticking to the insides of blood vessels, a process that can lead to dangerous blockages. The researchers compared white blood cells from men and pre-menopausal women blood donors. They found that cells from pre-menopausal women have much higher levels of a protein called annexin-A1 on the surface of their white blood cells. The scientists also found that annexin-A1 and estrogen levels were strongly linked throughout the menstrual cycle.

White blood cells play a vital part in protecting the body from infections. When they are activated, they stick to the walls of blood vessels. This process normally helps the cells to tackle infection but if it happens too much, it can lead to blood vessel damage, which in turn can lead to cardiovascular disease. When annexin-A1 is on the surface of these white blood cells, however, it prevents them from sticking to the blood vessel wall.

The new research shows that estrogen can move annexin-A1 from inside the white blood cell, where it is normally stored, to the surface of the cells. In laboratory experiments, treatment of the white blood cells with estrogen was enough to stop them from sticking to the surface of blood vessel walls.

The researchers believe that this could reveal a mechanism through which estrogen may protect against cardiovascular disease, by blocking the ability of white blood cells to stick to and damage blood vessel walls.

Dr Suchita Nadkarni from the William Harvey Research Institute (Queen Mary, University of London), who led the research, said: "We've known for a long time that estrogen protects pre-menopausal women from heart disease, but we don't know exactly why. This study brings us a step closer to understanding how natural estrogen might help protect our blood vessels.

"We've shown a clear relationship between estrogen levels and the behaviour of these white blood cells. Our results suggest that estrogen helps maintain the delicate balance between fighting infections, and protecting arteries from damage that can lead to cardiovascular disease.”

Of great interest is the potential role of estrogen in Hormone Replacement Therapy (HRT) in providing protection against cardiovascular disease and further research is needed to examine the effects of HRT on systems such as the immune system as described here. Meanwhile, current understanding is that HRT given in the early menopausal years is most likely protective.

[Reference]

< Go Back

<< News Index