Brain Immune Cells & Fertility: RANK Protein Link Revealed | Science News
The intricate dance of hormones that orchestrates puberty isn’t solely governed by the brain, according to a new study published in Science. Researchers at Spain’s National Cancer Research Centre (CNIO) have unexpectedly discovered that immune cells in the brain, specifically microglia, and a protein called RANK play a crucial role in sexual maturation. This finding, led by Eva González-Suárez, could reshape our understanding of reproductive development and potentially offer new avenues for addressing infertility.
A Surprising Connection: Brain Immunity and Reproduction
For decades, the hypothalamic-pituitary-gonadal (HPG) axis has been understood as the central regulator of puberty. This system begins with neurons in the hypothalamus releasing hormones that activate the pituitary gland, which then signals the ovaries or testes to mature. However, the CNIO study reveals that this hormonal cascade isn’t operating in isolation. Microglia, the resident immune cells of the central nervous system, are actively involved in modulating the function of gonadotropin-releasing hormone (GnRH) neurons – the key players initiating puberty.
“Finding fertility-regulating cells that are not neurons, but rather immune cells, is crucial,” emphasizes González-Suárez. The link between microglia and GnRH neurons is the RANK protein, previously known for its role in bone remodeling and mammary gland development. González-Suárez’s group first identified the key role played by RANK in the development of breast cancer back in 2010. Her work continues to illuminate the multifaceted functions of this protein.
How RANK Impacts Reproductive Function
The research, conducted initially in animal models, demonstrated that suppressing RANK expression led to distorted reproductive function in both males, and females. Animals lacking RANK, or with the protein removed before puberty, experienced reduced sex hormone levels, impaired gonad function (hypogonadism), and delayed puberty. Even in sexually mature animals, eliminating RANK resulted in infertility within a month. This suggests that RANK is not just involved in initiating puberty, but as well in maintaining ongoing reproductive capacity.
The study’s findings aren’t limited to laboratory animals. Researchers also identified genetic mutations in the gene encoding the RANK protein in patients with congenital hypogonadotropic hypogonadism, a rare genetic syndrome characterized by delayed or absent puberty and infertility. This provides a crucial link between the animal model findings and human health.
Implications for Human Fertility and Beyond
The discovery of RANK’s role in fertility opens up potential new therapeutic targets for endocrine disorders and syndromes affecting reproduction. The authors suggest that RANK could be a candidate gene for molecular diagnosis of congenital hypogonadotropic hypogonadism. As reported by News-Medical.net, this research offers a novel perspective on the complex interplay between the immune system and reproductive health.
González-Suárez also points to the broader implications of this research. “The role of microglia in regulating the function of ‘reproductive’ neurons is new, and this regulation associated with RANK can occur in other axes, for other functions, such as the appetite-satiety axis, the stress axis, etc.” This suggests that microglia and RANK may be involved in a wider range of physiological processes than previously understood.
Understanding Congenital Hypogonadotropic Hypogonadism
Congenital hypogonadotropic hypogonadism (CHH) is a genetic condition affecting the production of reproductive hormones. The CNIO research suggests that mutations in the RANK gene could be a contributing factor in some cases of CHH, adding to the known causes which include problems with GnRH neurons or the molecules they produce. This discovery could lead to improved diagnostic tools and potentially targeted therapies for individuals affected by this condition.
The Importance of Interdisciplinary Collaboration
The success of this study highlights the value of collaboration across scientific disciplines. Alejandro Collado, the first author of the study, explains that the research began with an investigation into RANK’s role in mammary tissue development. “When we realised that we needed to explore issues implying fertility, neurons and brain cells, we started consulting colleagues from other fields.” This interdisciplinary approach allowed the researchers to uncover the unexpected link between brain immunity and reproductive function.
The study, titled “Microglia Rank signaling regulates GnRH neuronal function and the hypothalamic-pituitary-gonadal axis,” was published in Science in March 2026 (DOI: 10.1126/science.aeb6999). Further research will be needed to fully elucidate the mechanisms by which microglia and RANK regulate reproductive function and to explore the potential for therapeutic interventions. For now, this study represents a significant step forward in our understanding of the complex interplay between the brain, the immune system, and reproductive health.
Looking Ahead: Researchers are now focused on investigating the specific signaling pathways involved in RANK’s regulation of GnRH neurons. Clinical trials may eventually be considered to assess the safety and efficacy of targeting RANK for the treatment of infertility and other reproductive disorders. Ongoing surveillance and research will be crucial to translate these findings into improved patient care.