Do ovaries take on a new immunity role after menopause?

Postmenopausal ovaries may remain active by interacting with immune cells. The findings of a new study could widen understanding of ageing and women's health after menopause.

In Short

• Researchers studied ovaries removed from postmenopausal women aged 50 to 75
• Older ovarian tissue showed changing proteins, suggesting continued biological activity
• Mouse analysis found immune cells increased as reproductive function declined

For decades, scientists believed that once menopause arrived, the ovary had little left to do.

Without eggs to release and hormones to produce, the organ was largely viewed as biologically inactive, a leftover from a woman's reproductive years, much like an appendix that no longer serves a meaningful purpose.

That assumption is now being challenged.

New research from scientists at Northwestern University Feinberg School of Medicine suggests that the ovary may not retire after menopause after all. Instead, it could begin performing an entirely different role: interacting with the body's immune system.

The findings, published in Molecular Human Reproduction, offer an intriguing glimpse into what happens inside the ageing ovary long after fertility ends, and may eventually help explain why women's health often changes dramatically after menopause.

DO OVARIES CHANGE THEIR FUNCTION POST MENOPAUSE?

This research shifts scientists' view of the post-reproductive ovary from being an empty shell to something with a potentially new function.

The discovery surprised even the scientists leading the work.

Francesca Duncan, a reproductive biologist at Northwestern University, had joined a US National Institutes of Health initiative to study ageing cells known as senescent cells. These cells stop dividing as we age and are increasingly believed to contribute to inflammation and age-related diseases.

Her initial goal was straightforward: map these ageing cells inside human ovaries.

There was one challenge.

Healthy ovaries from younger women are rarely available for research, so Duncan's team focused on ovaries removed from postmenopausal women between the ages of 50 and 75 during medically necessary surgeries.

At first, Duncan was disappointed. She expected to study organs that had effectively shut down.

Instead, she found something unexpected.

The ovaries continued to change with age.

Different proteins appeared in older ovaries, suggesting the tissue remained biologically active even years after menopause. If the organ truly had no purpose, Duncan reasoned, scientists would expect it to look largely unchanged across ageing.

"It highlighted to us that there's something else going on with this organ," she told Science.

To understand those changes better, the researchers turned to laboratory mice.

They examined ovaries from young mice, mice nearing the end of their reproductive years and older mice that had stopped reproducing. One ovary from each animal underwent genetic sequencing to identify which genes were active, while the other was examined under a microscope to study tissue changes.

WHAT WERE THE FINDINGS?

Some findings were expected.

Genes involved in egg production and hormone synthesis steadily declined with age.

But another pattern stood out.

Older ovaries became increasingly populated by immune cells. They also showed greater activity of genes linked to inflammatory molecules, proteins that could potentially circulate through the bloodstream and influence other organs.

Whether the ageing ovary actively directs immune responses or simply becomes a gathering place for immune cells remains unknown.

The ovary might become a site where immune cells come and get changed in some way that could have effects throughout the body.

Although the work was conducted largely in mice, researchers say the findings open a new avenue for understanding women's health after menopause.

MENOPAUSE CONTRIBUTES TO IMMUNITY?

Scientists have long known that women experience a sharp rise in risks of cardiovascular disease, osteoporosis and several chronic conditions after menopause. Much of that has been attributed to declining oestrogen levels.

The new findings raise another possibility: that the ovary itself may continue influencing health through the immune system, even after reproduction has ended.

If confirmed, this could reshape how scientists think about ageing in women and why chronic inflammation becomes more common later in life.

For Duncan, the study also highlights how little is known about an organ that half the world's population carries for much of their lives.

"The gap in our knowledge of the postmenopausal ovary is a little bit frightening," she said. "We really owe it to women's health to study this period of time."

The answers may not arrive immediately.

But what was once dismissed as a biologically inactive organ is now emerging as one of the newest frontiers in ageing research, suggesting that menopause may mark not the end of the ovary's story, but the beginning of an entirely different chapter.

- Ends