title: MMP-3 secreted from endothelial cells of blood vessels after spinal cord injury activates microglia, leading to oligodendrocyte cell death.
abstract: The activation of microglia after spinal cord injury (SCI) contributes to secondary damage by producing pro-inflammatory cytokines and mediators, leading to cell death of oligodendrocytes and neurons. Here, we show that matrix metalloprotease-3 (MMP-3) produced and secreted in the endothelial cells of blood vessels after SCI mediates microglial activation. MMP-3 was produced and secreted in bEnd.3 cells, a mouse brain-derived endothelial cell line, by oxygen-glucose deprivation/reoxygenation (OGD/RO). OGD/RO-induced MMP-3 expression and activity was also significantly inhibited by ghrelin, which was dependent on the ghrelin receptor GHS-R1a. Furthermore, the secreted MMP-3 from OGD/RO-induced bEnd.3 cells activated BV-2 cells, a murine microglial cell line. We also found that microglial activation after SCI was attenuated in MMP-3 knockout (KO) mice compared with wild type (WT) mice. Both p38 mitogen-activated protein kinase (MAPK) activation and pro-nerve growth factor (proNGF) production were more inhibited in MMP-3 KO than WT mice at 5d after injury. When WT mice were treated with Mmp-3 siRNA after injury, MMP-3 activity, microglial activation, p38MAPK activation and proNGF expression were significantly inhibited. Ghrelin treatment also significantly inhibited MMP-3 expression and activation after SCI, which was dependent on GHS-R1a. Finally, RhoA activation and oligodendrocyte cell death after injury were attenuated by Mmp-3 siRNA or ghrelin treatment compared with vehicle control. Thus, our study indicates that MMP-3 produced in blood vessel endothelial cells after SCI serves as an endogenous molecule for microglial activation followed by p38MAPK activation and proNGF production, and further indicates that the protective effect of ghrelin on oligodendrocytes cell death may be at least partly mediated by the inhibition of MMP-3-induced microglial activation after SCI.
authors.affiliation: Age-Related and Brain Diseases Research Center, School of Medicine, Kyung Hee University, Seoul 130-701, Republic of Korea. Electronic address: jeeyoun@hu.ac.kr.
authors.forename: Jee Y
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Age-Related and Brain Diseases Research Center, School of Medicine, Kyung Hee University, Seoul 130-701, Republic of Korea. Electronic address: neuron@khu.ac.kr.
authors.forename: Hae Y
authors.initials: HY
authors.lastname: Choi
authors.affiliation: Age-Related and Brain Diseases Research Center, School of Medicine, Kyung Hee University, Seoul 130-701, Republic of Korea; Department of Biochemistry and Molecular Biology, School of Medicine, Kyung Hee University, Seoul 130-701, Republic of Korea. Electronic address: tyune@khu.ac.kr.
authors.forename: Tae Y
authors.initials: TY
authors.lastname: Yune
mesh_terms: D000818:Animals; D016923:Cell Death / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D054439:Ghrelin / Q000494:pharmacology; D019278:Matrix Metalloproteinase 3 / Q000378:metabolism*; D051379:Mice; D017628:Microglia / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D009414:Nerve Growth Factors / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009836:Oligodendroglia / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D013119:Spinal Cord Injuries / Q000378:metabolism* / Q000473:pathology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D054439:Ghrelin; D009414:Nerve Growth Factors; D048051:p38 Mitogen-Activated Protein Kinases; D019278:Matrix Metalloproteinase 3
keywords: Matrix metalloprotease-3; Microglia; Oligodendrocyte; RhoA; Spinal cord injury