Abstract Sun207: Upregulated Bach1 aggreaviated brain injury after cardiopulmonary resuscitation in mice through enhancing brain microvascular endothelial cell endocytosis

Background: Persistent cognitive impairment and anxiety-depressive states occur in 20-30% of return of spontaneous circulation (ROSC) patients, manifesting as diffuse cerebral edema. Brain microvascular endothelial cell (BMEC) dysfunction is a critical factor contributing to post-ROSC cerebral edema. Bach1, highly expressed in endothelial cells, acts as a negative transcriptional regulator and may participate in the regulation of BMECs dysfunction by modulating endocytosis. However, the specific mechanism remains unclear. Methods: We performed a transcriptomics study and RT-qPCR to screen differentially expressed Ischemia/hypoxia-related genes in cerebral microvascular segments of mice after ROSC. Using Western Blot and immunofluorescence to profile Bach1 expression in BMECs. Constructed BMEC-specific conditional Bach1 knockout mice（Bach1cKO-Tie） to evaluate the impact of detected Bach1 in BMECs on ROSC survival rate, neurological function, cerebral edema, and endocytosis-related functions. Furthermore, we employed an endocytosis agonist, in conjunction with transmission electron microscopy and Dil immunofluorescence staining, to elucidate the mechanisms by which Bach1 influences BMEC function through enhancing endocytosis. Results: We found a significant increase in Bach1 expression in mouse brain microvascular segments after ROSC. Conditionally detected Bach1 in BMECs significantly improved survival rate, neurological functional outcomes following ROSC and ameliorated cerebral edema. In addition, endocytosis-related barrier proteins ZO-1 and claudin-5 expression increase, and BMECs' endocytosis is attenuated. The endocytosis agonist Jasplakinolide partially reversed the reduction in BMEC endocytosis caused by Bach1 knockout. Conclusion: Together, these results suggest that upregulated Bach1 in BMECs exacerbates brain injury following ROSC through enhancing endocytosis. Furthermore, Bach1 may constitute a new therapeutic target for brain injury after ROSC.