Nuclear heme oxygenase-1 enhances blood-spinal cord barrier repair via corticotropin-releasing hormone-mediated tight junction phosphorylation.

OBJECTIVE

The hallmark of secondary spinal cord injury (SCI) is destruction of the blood-spinal cord barrier (BSCB). Nuclear heme oxygenase-1 (NHO-1) is involved in neuroprotection in the central nervous system. Previously, we demonstrated that adenoviral delivery of nuclear-targeted HO-1 (NHO-1) alleviates BSCB disruption, but the molecular mechanisms remain to be clarified. This study was conducted to investigate the specific regulatory mechanisms regulating tight junctions in the BSCB.

METHODS

A moderate T10 contusion SCI was induced in adult male Sprague-Dawley rats. Nuclear-targeted HO-1 was delivered by adenoviral pretreatment 7 days before injury. Spinal cords were collected at 24 h post-SCI for RNA-seq and quantitative real-time-PCR validation. BSCB permeability (Evans Blue), tight junction phosphorylation (western blot), and locomotor function (Basso, Beattie, and Bresnahan score and footprint analysis) were assessed, with intrathecal corticotropin-releasing hormone (CRH)-R1 agonist (Cortagine) or antagonist (Antalarmin) administered after SCI.

RESULTS

RNA-seq identified 10 overlapping differentially expressed genes across pairwise comparisons; subsequent Venn-based prioritization and quantitative real-time-PCR validation identified Crh as the most consistently regulated candidate. Functional assays demonstrated that nuclear HO-1, particularly when combined with CRH receptor activation, decreased leakage of BSCB via enhancing phosphorylation of tight junction protein which disappears after application of CRH inhibitor.

CONCLUSION

These results indicate that nuclear-targeted HO-1 promotes BSCB repair after SCI by transcriptionally upregulating Crh and enhancing CRH-dependent phosphorylation of tight junction proteins (Claudin-5 and Occludin).