Scientists Identify IL-11 as a Potential Target for Preserving Female Fertility

Scientists have identified a way to preserve the flexibility of aging mouse ovaries by blocking a protein involved in tissue stiffening, a discovery that could eventually contribute to new approaches for extending female fertility. The research focuses on the ovarian extracellular matrix—a gel-like network of proteins that surrounds and supports reproductive cells.

The extracellular matrix is not uniform throughout the ovary. Primordial follicles, which store immature eggs for many years, are located in a relatively stiff region that helps keep them dormant and protected. In contrast, follicles preparing for ovulation develop within a softer environment that allows them to expand and receive nutrients.

How Ovarian Tissue Changes With Age

As ovaries age, they accumulate damage from oxidative stress, chronic inflammation, and other biological stressors. Over time, this contributes to fibrosis—a buildup of collagen-rich scar tissue that makes the ovarian extracellular matrix stiffer and less capable of supporting healthy egg development.

Researchers have long suspected that this progressive stiffening contributes to declining fertility and the transition to menopause. A more rigid ovarian environment may disrupt the complex signaling required for follicles to mature properly, potentially reducing the remaining pool of viable eggs.

A research team led by scientists at Huazhong University of Science and Technology in China sought to identify the mechanisms responsible for this fibrotic remodeling. Their study, published in Nature Aging, identifies the signaling protein interleukin-11 (IL-11) as a central regulator of ovarian matrix stiffness.

IL-11 Emerges as a Key Driver

To investigate age-related changes in ovarian tissue, the researchers analyzed healthy ovaries removed from women undergoing surgery for cervical or endometrial cancer, where the ovaries themselves showed no evidence of cancer. Participants were divided into reproductively young, middle-aged, and older groups.

The researchers also examined ovarian tissue from women aged 30 to 40 who had medical conditions known to impair ovarian function. These included chemotherapy-induced premature ovarian insufficiency, a metabolic condition described by the authors as polyendocrine metabolic ovarian syndrome, and ovarian endometriosis.

Across these tissue samples, markers of ovarian aging and disease were consistently associated with increased extracellular matrix stiffness. Using RNA sequencing and proteomic analyses, the researchers identified IL-11 and its receptor component, Il11ra1, as major drivers of fibroblast activation. Fibroblasts are the cells responsible for producing collagen and other structural components of connective tissue.

IL-11 levels increased with age not only in human ovarian tissue but also in mice and rats. The researchers report that aging, chemotherapy, polycystic-like ovarian syndromes, and endometriosis all appeared to increase IL-11 production, promoting fibrosis and progressive stiffening of ovarian tissue.

Reversing Ovarian Stiffness in Mice

Having identified IL-11 as a potential therapeutic target, the researchers investigated whether blocking its activity could preserve a more youthful ovarian environment in mice. One approach involved genetically deleting the Il11 gene, while another used RNA-loaded nanoparticles designed to suppress IL-11 production specifically within ovarian tissue.

Both strategies reduced collagen accumulation and decreased overall ovarian stiffness in older mice. Importantly, treated animals also showed improved reproductive performance, producing more offspring per pregnancy than untreated mice of similar age.

These findings support the existence of a biological feedback loop in which the hallmarks of ovarian aging promote fibrosis and tissue stiffening, which in turn accelerates further ovarian decline. By interrupting this process through IL-11 inhibition, the researchers were able to partially restore ovarian function in their animal models.

Implications for Menopause and Infertility

The study raises the possibility that future therapies targeting IL-11 could help delay menopause or preserve fertility, particularly in patients undergoing treatments known to damage the ovaries. Infertility and premature loss of ovarian function affect tens of millions of people worldwide, while currently available fertility-preservation options remain limited.

Biomedical researcher Stuart Cook, who was not involved in the study, noted in an accompanying commentary that drugs targeting IL-11 are already undergoing clinical trials for several fibrotic diseases. Existing drug development programs could potentially accelerate future research into reproductive applications.

Cook suggested that, provided safety and effectiveness can be demonstrated, anti-IL-11 therapies might eventually be investigated for preventing chemotherapy-induced premature ovarian insufficiency or treating forms of polycystic ovary syndrome associated with ovarian fibrosis. Such treatments would aim to preserve tissue quality rather than directly alter hormone levels.

However, researchers emphasize that the work remains at an early stage. Important biological differences exist between mouse and human ovaries, and attempts to preserve fertility raise complex medical and ethical questions, including potential effects on cancer risk and long-term hormonal health.

Next Steps and Remaining Questions

Future studies will need to determine how long IL-11 suppression can be maintained safely and whether improvements in ovarian function persist after treatment ends. Researchers also hope to clarify how IL-11 interacts with other inflammatory and fibrotic pathways involved in ovarian aging.

Before human clinical trials could begin, investigators would need to identify patients most likely to benefit, such as individuals preparing to undergo gonadotoxic chemotherapy or those with confirmed ovarian fibrosis. Developing reliable, non-invasive methods to measure ovarian stiffness and fibrosis will also represent an important technical challenge.

Despite these unanswered questions, the study adds to growing evidence that the physical characteristics of tissues—not only hormones and genetics—play an important role in reproductive aging. By focusing on the stiffness of the ovarian microenvironment, researchers may have identified a new therapeutic target for preserving fertility.

The authors conclude that blocking IL-11 signaling in both normal ovarian aging and several disease models shows considerable therapeutic potential. Although clinical applications remain several years away, the findings offer cautious optimism for people seeking to preserve their reproductive health in the future.