Subarachnoid haemorrhage (SAH) is a form of stroke that can occur spontaneously or as a result of head injury. Treatment options are limited, and few experimental models recapitulate the key features of the condition. Using a recently developed rat model that closely mimics human SAH, Greenhalgh et al. now show that blocking the IL-1 pathway using its endogenous receptor antagonist, IL-1Ra, lessens CNS pathology. They also show that haem, a breakdown product of haemoglobin derived from lysed erythrocytes in the subarachnoid space, drives IL-1 production and neuronal death. These results suggest that haem acts as a danger signal driving CNS inflammation, and that IL-1Ra – a therapy already approved for other indications – might be a promising treatment for SAH. Page 823

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