Cranial photo-immunologic regulation along the skull-meninges-brain axis for promoting recovery from ischemic brain injury

Stroke involves in the interaction between central and peripheral immune systems. Skull bone marrows serve as reservoirs for immune cells in brain borders, and can rapidly respond to perturbations in the brain environment. Hence, targeting the skull bone marrow to modulate neuroimmune communications along the calvaria-meninges-brain axis would potentially improve stroke prognosis. Here, we successfully achieved cranial immunomodulation via ultraviolet (UV) irradiation of the interparietal region, which was characterized by rich marrow cavities and channels connecting the skull and meninges. Utilizing the recently-developed long-term clearing cranial window that ensured the integrity of skull, we discovered that the cranial photo-immunologic regulation (CPR) could promote cerebrovascular regeneration and aid in neurovascular repair post ischemic stroke. Single-cell transcriptome analysis revealed that meninge could be a crucial neuroimmune interface for ischemic stroke-induced immune responses. And, CPR could restore the stroke-induced alterations in cellular gene expression, especially meningeal B cells. Further we demonstrated that CPR could effectively alleviate the excessive suppression of meningeal B cell activation caused by ischemic stroke. This work opens avenues for immunoregulation through the skull-meninges-brain axis and provides valuable insights for immunomodulatory therapies in brain diseases. Overall design: Single-cell transcriptomic profiling was performed on Sham, tMCAO (transient middle cerebral artery occlusion), and tMCAO+UVB(ultraviolet B) treated mouse skull, meninges, and brain tissue separately.

脑卒中涉及中枢与外周免疫系统的相互作用。颅骨骨髓是脑边界处免疫细胞的储存库，可快速响应脑环境的异常变化。因此，靶向颅骨骨髓以调控沿颅盖-脑膜-脑轴的神经免疫交流，或可改善脑卒中预后。本研究通过对顶间区（该区域富含骨髓腔及连接颅骨与脑膜的通道）进行紫外线（ultraviolet, UV）照射，成功实现了颅骨免疫调控。借助新近开发的可保障颅骨完整性的长期透明化颅骨窗技术，本研究发现颅骨光免疫调控（cranial photo-immunologic regulation, CPR）可促进缺血性脑卒中后的脑血管再生，助力神经血管修复。单细胞转录组分析显示，脑膜或是介导缺血性脑卒中诱导免疫应答的关键神经免疫界面。此外，CPR可恢复脑卒中诱导的细胞基因表达异常，尤其是脑膜B细胞的表达紊乱。进一步研究证实，CPR可有效缓解缺血性脑卒中引发的脑膜B细胞活化过度抑制状态。本研究为通过颅骨-脑膜-脑轴实施免疫调控开辟了新路径，并为脑部疾病的免疫调控疗法提供了重要参考。总体实验设计：分别对假手术（Sham）组、短暂性大脑中动脉闭塞（transient middle cerebral artery occlusion, tMCAO）组以及tMCAO联合紫外线B（ultraviolet B, UVB）处理组的小鼠颅骨、脑膜及脑组织进行单细胞转录组测序分析。