Cranial photoregulation reshapes brain border immunity and promotes recovery after stroke

The skull bone marrow represents a targetable neuroimmune interface adjacent to the brain borders with the potential to improve stroke outcomes. Here, we identified the skull as a highly responsive immune niche and developed a cranial photo-immunologic regulation (CPR) strategy using low-dose, narrow-band medical UVB. Targeted irradiation of the interparietal region reshapes brain border immune crosstalk, effectively promoting repair and functional recovery after ischemic injury. Mechanistically, UVB-based CPR reverses stroke-induced suppression of meningeal B cell activation, contributing to restoring brain border immune homeostasis. Depletion of meningeal B cells further demonstrates that these cells are required for the therapeutic effects of CPR. These findings establish the skull as an actionable target for neuroimmune modulation along the skull–meninges–brain axis and provide a potentially transformative strategy for treating neurological disease.