ABSTRACT
The disruption of the blood-spinal cord barrier (BSCB) by matrix metalloprotease (MMP) activation is a detrimental event that leads to blood cell infiltration, inflammation, and apoptosis, thereby contributing to permanent neurological disability after spinal cord injury (SCI). However, the molecular mechanisms underlying Mmp gene regulation have not been fully elucidated. Here, we demonstrated the critical role of histone H3K27 demethylase Jmjd3 in the regulation of Mmp gene expression and BSCB disruption using in vitro cellular and in vivo animal models. We found that Jmjd3 up-regulation, in cooperation with NF-κB, after SCI is required for Mmp-3 and Mmp-9 gene expressions in injured vascular endothelial cells. In addition, Jmjd3 mRNA depletion inhibited Mmp-3 and Mmp-9 gene expressions and significantly attenuated BSCB permeability and the loss of tight junction proteins. These events further led to improved functional recovery, along with decreased hemorrhage, blood cell infiltration, inflammation, and cell death of neurons and oligodendrocytes after SCI. Thus, our findings suggest that Jmjd3 regulation may serve as a potential therapeutic intervention for preserving BSCB integrity following SCI.
Subject(s)
Gene Expression Regulation/genetics , Jumonji Domain-Containing Histone Demethylases/metabolism , Matrix Metalloproteinase 3/metabolism , Matrix Metalloproteinase 9/metabolism , Spinal Cord Injuries/metabolism , Spinal Cord Injuries/physiopathology , Animals , Blood-Brain Barrier , Capillary Permeability/genetics , Endothelial Cells/metabolism , Male , NF-kappa B/metabolism , Rats, Sprague-Dawley , Recovery of Function/physiology , Spinal Cord/metabolism , Up-RegulationABSTRACT
Blood-spinal cord barrier (BSCB) disruption and progressive hemorrhage after spinal cord injury (SCI) lead to secondary injury and the subsequent apoptosis and/or necrosis of neuron and glia, causing permanent neurological deficits. In this study, we examined the effect of 17ß-estradiol (E2) on BSCB breakdown and hemorrhage as well as subsequent inflammation after SCI. After a moderate contusion injury at the 9th thoracic segment of spinal cord, E2 (300 µg/kg) was administered by iv injection immediately after SCI, and the same dose of E2 was then administered 6 and 24 hours after injury. Our data show that E2 attenuated BSCB permeability and hemorrhage and reduced the infiltration of neutrophils and macorphages after SCI. Consistent with this finding, the expression of inflammatory mediators was significantly reduced by E2. Furthermore, E2 treatment significantly inhibited the expression of sulfonylurea receptor 1 and transient receptor potential melastatin 4 after injury, which are known to mediate hemorrhage at an early stage after SCI. Moreover, the expression and activation of matrix metalloprotease-9 after injury, which is known to disrupt BSCB, and the degradation of tight junction proteins, such as zona occludens-1 and occludin, were significantly inhibited by E2 treatment. Furthermore, the protective effects of E2 on BSCB disruption and functional improvement were abolished by an estrogen receptor antagonist, ICI 182780 (3 mg/kg). Thus, our study provides evidence that the neuroprotective effect of E2 after SCI is, in part, mediated by inhibiting BSCB disruption and hemorrhage through the down-regulation of sulfonylurea receptor 1/transient receptor potential melastatin 4 and matrix metalloprotease-9, which is dependent on estrogen receptor.
Subject(s)
Blood-Brain Barrier/drug effects , Capillary Permeability/drug effects , Estradiol/pharmacology , Hemorrhage/metabolism , Matrix Metalloproteinase 9/drug effects , Spinal Cord Injuries/metabolism , Sulfonylurea Receptors/drug effects , TRPM Cation Channels/drug effects , Animals , Apoptosis , Blood-Brain Barrier/metabolism , Down-Regulation/drug effects , Estradiol/analogs & derivatives , Estrogen Receptor Antagonists/pharmacology , Fulvestrant , Male , Matrix Metalloproteinase 9/metabolism , Rats , Rats, Sprague-Dawley , Sulfonylurea Receptors/metabolism , TRPM Cation Channels/metabolismABSTRACT
Blood spinal cord barrier (BSCB) disruption after spinal cord injury (SCI) leads to secondary injury and results in apoptosis of neurons and glia, leading to permanent neurological deficits. Here, we examined the effect of ghrelin on BSCB breakdown and hemorrhage after SCI. After moderate weight-drop contusion injury at T9 spinal cord, ghrelin (80µg/kg) was administered via intraperitoneal injection immediately after SCI and then the same dose of ghrelin was treated every 6h for 1d. Our data showed that ghrelin treatment significantly inhibited the expression and activation of matrix metalloprotease-9 (MMP-9) at 1d after SCI. The increases of sulfonylurea receptor 1 (SUR1) and transient receptor potential melastatin 4 (TrpM4) expressions at 1h and 8h after SCI respectively were also alleviated by ghrelin treatment. In addition, both BSCB breakdown and hemorrhage at 1d after injury were significantly attenuated by ghrelin. In parallel, the infiltration of blood cells such as neutrophils and macrophages was inhibited by ghrelin treatment at 1d and 5d after SCI respectively. We also found that ghrelin receptor, growth hormone secretagogue receptor-1a (GHS-R1a), was expressed in the blood vessel of normal spinal tissue. Furthermore, the inhibitory effects of ghrelin on hemorrhage and BSCB disruption at 1d after SCI were blocked by GHS-R1a antagonist, [D-Lys-3]-GHRP-6 (3mg/kg). Thus, these results indicate that the neuroprotective effect by ghrelin after SCI is mediated in part by blocking BSCB disruption and hemorrhage through the down-regulation of SUR1/TrpM4 and MMP-9, which is dependent on GHS-R1a.
