Could a Pregnancy Hormone Help Calm Autoimmune Inflammation?
Doctors have long noticed that some autoimmune diseases temporarily improve during pregnancy. A new study published in Nature Immunology may now explain why.
Researchers found that levels of a molecule called GDF-15 rise during pregnancy and are linked to fewer relapses in people with multiple sclerosis (MS), a disease in which the immune system attacks the brain and spinal cord, damaging nerves and disrupting communication between the brain and body.
The discovery reveals a previously unrecognized role for GDF-15 in a signaling pathway connecting pregnancy biology, the brain, and the immune system.
The study suggests that GDF-15 activates specialized neurons in the brainstem, triggering the release of norepinephrine, a chemical messenger involved in alertness, heart rate, and immune regulation. This signal appears to calm CD4⁺ T cells, key white blood cells that coordinate immune responses, limiting their ability to enter the brain and reducing inflammation.
To test the pathway, scientists gave lab-made GDF-15 to mice. In separate experiments, mice lacking GDF-15 developed more severe inflammation and had lower survival rates, while increasing GDF-15 reduced disease severity and prevented immune cells from infiltrating the central nervous system.
What surprised researchers most though was not the effect itself, but how it happened. Rather than directly suppressing immune cells, GDF-15 worked by altering signals sent through the nervous system. This finding suggests that communication between the brain and immune system may play a much larger role in autoimmune disease than previously understood. These results add to growing evidence that the immune system does not function in isolation — it is shaped by neural signals. Instead of broadly suppressing immunity, future therapies might aim to fine-tune this brain–immune communication, potentially offering more targeted treatment with fewer side effects.
Because compounds affecting GDF-15 signaling have already been studied in clinical trials for metabolic conditions, researchers suggest that existing drugs could potentially be repurposed to treat inflammatory diseases like multiple sclerosis if future studies confirm safety and effectiveness.
Although this study focused on MS, the brain–immune signaling pathway it identified could have implications for other autoimmune and inflammatory diseases in which immune cells mistakenly attack healthy tissue.
More broadly, the study provides a biological explanation for a long-recognized observation: pregnancy can temporarily calm inflammatory disease activity. By identifying the underlying mechanism and linking it to a measurable biological pathway, researchers may be able to design therapies that safely mimic those protective effects outside of pregnancy and support the development of more targeted treatments for autoimmune diseases.