New research from La Trobe University and the Baker Heart and Diabetes Institute has revealed that the spleen could be a crucial new target for improving recovery after stroke.
The study, published in Frontiers in Immunology, found that the spleen produces inflammatory immune cells following a stroke, which can worsen brain injury. By blocking a specific inflammatory signal known as S100A8/A9 in experimental models, researchers were able to reduce brain damage by about one-third and improve recovery outcomes.
Stroke is one of the world’s leading causes of death and long-term disability. Current treatments focus on restoring blood flow to the brain, but they do not address the damaging inflammation that continues after the initial blockage is cleared.
Lead researcher Dr Helena Kim from La Trobe University said the findings point to a new way to help stroke patients recover. “Inflammation can cause ongoing injury to the brain, even after blood flow is restored,” Dr Kim said. “Our findings show there may be new ways to limit this damage by targeting the body’s immune response.”
The study found that after a stroke, the protein signal S100A8/A9 acts like an alarm, triggering the body to produce more inflammatory cells. While this response is meant to help repair damage, it can instead make things worse by increasing swelling and harming brain tissue.
To test whether this process could be controlled, the researchers used a drug that blocked S100A8/A9. In animal models, those treated with the drug before and after stroke had fewer inflammatory cells in the spleen and blood, smaller areas of brain damage, and better physical recovery within 24 hours.
Senior scientist Dr Sam Lee from the Baker Heart and Diabetes Institute said the discovery highlights the spleen’s unexpected role in stroke-related inflammation. “We discovered that most of these inflammatory immune cells actually come from the spleen,” Dr Lee said. “This helps explain why inflammation spreads throughout the body after stroke and identifies the spleen as an important new therapeutic target.”
The team also examined brain tissue from people who had suffered severe strokes and found the same inflammatory signal in damaged areas, confirming the findings are relevant to human disease.
Dr Kim said the research opens the door to new treatments that could complement existing therapies. “Rather than wiping out immune cells altogether, which can be dangerous, this approach aims to switch off the signals that cause excessive and damaging inflammation,” she said.
Further studies will explore whether the same approach could help other conditions linked to inflammation, such as heart attacks and vascular disease. DOI: https://doi.org/10.3389/fimmu.2026.1768647
