Washington, Oct 26: Researchers at the Royal Veterinary College, London have studied the effect of infections in the uterus of cows which might help in providing clues for preventing infertility in humans.

The breakthrough study led by Professor Martin Sheldon found common uterine infections could damage the ovaries in cows, which may provide insights into the treatment of infections such as Chlamydia in humans.

The findings suggest that the cow's instinctive immune system might affect key stages in the reproductive cycle, including suppressing the release of the female sex hormone oestrogen and causing failure to ovulate.

Uterine diseases not only affect milk production but also the cow's ability to reproduce. In cows, uterine disease is usually caused by bacteria entering the uterus after the cow has given birth.

The same route of infection can also occur in women. However, humans may also be affected by sexually transmitted infections such as Chlamydia.

Although the infections are usually successfully treated with antibiotics, the infertility often persists.

The team used the bacterium E. coli to examine the effect that bacteria had on the granulosa cells that lined each egg-containing follicle in the ovary.

The egg was nurtured by the granulosa cells until the follicle burst the egg, and they made oestradiol, a form of the sex hormone oestrogen, which encourages the female to copulate.

The team found that even after being treated for uterine disease, the follicle still contained toxin left over from the breakdown of the pathogen.

It was also found that granulosa cells, which protect the egg inside the follicle, played a part in the immune response to infection by recognising that the toxin had entered the follicle and inhibited the production of oestradiol.

"We believe that granulosa cells may play a role in 'quality control' relating to ovulation," Sheldon said.

"Infection can potentially damage the genetic make-up of an egg, and these 'errors' would be passed down from generation to generation. By suppressing the release of oestrogen – in effect, reducing sexual behaviour – the granulosa are preventing those defects being passed on,” he said.

"It appears that bacteria have a lasting effect on fertility in cattle and possibly humans. Our research suggests a mechanism for how this may occur and offers hope for developing new treatments to prevent this from happening,” he added.

The study is published in the journal Reproduction. (ANI)