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Astrocyte-targeted expression of interleukin-6 protects the central nervous system during neuroglial degeneration induced by 6-aminonicotinamide

Department of Medical Anatomy, The Panum Institute, University of Copenhagen, Copenhagen, Denmark.
Journal of Neuroscience Research (Impact Factor: 2.73). 08/2003; 73(4):481-96. DOI: 10.1002/jnr.10681
Source: PubMed

ABSTRACT 6-aminonicotinamide (6-AN) is a niacin antagonist, which leads to degeneration of gray matter astrocytes mainly in the brainstem. We have examined the role of interleukin-6 (IL-6) in this degenerative process by using transgenic mice with astrocyte-targeted IL-6 expression (GFAP-IL6 mice). This study demonstrates that transgenic IL-6 expression significantly increases the 6-AN-induced inflammatory response of reactive astrocytes, microglia/macrophages, and lymphocytes in the brainstem. Also, IL-6 induced significant increases in proinflammatory cytokines IL-1, IL-12, and tumor necrosis factor-alpha as well as growth factors basic fibroblast growth factor (bFGF), transforming growth factor-beta, neurotrophin-3, angiopoietin, vascular endothelial growth factor, and the receptor for bFGF. In accordance, angiogenesis was increased in GFAP-IL6 mice relative to controls after 6-AN. Moreover, oxidative stress and apoptotic cell death were significantly reduced by transgenic IL-6 expression. IL-6 is also a major inducer in the CNS of metallothionein I and II (MT-I+II), which were significantly increased in the GFAP-IL6 mice. MT-I+II are antioxidants and neuroregenerative factors in the CNS, so increased MT-I+II levels in GFAP-IL6 mice could contribute to the reduction of oxidative stress and cell death in these mice.

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    • "IL-6 was found at elevated levels in experimental TBI (Shohami et al., 1994). Mice deficient for IL-6 had increased numbers of apoptotic neurons, increased oxidative stress and delayed healing of the tissue (Penkowa et al., 2000), whereas the same group demonstrated that IL-6 transgenic mice exhibited increased reduction of oxidative stress and apoptotic cell death after a cryogenic brain injury (Penkowa et al., 2003). Tumor necrosis factor-a (TNFa) is another cytokine with a well-documented role in TBI. "
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