title: Improved recovery and delayed cytokine induction after closed head injury in mice with central overexpression of the secreted isoform of the interleukin-1 receptor antagonist.
abstract: The acute inflammatory response following traumatic brain injury (TBI) has been shown to play an important role in the development of secondary tissue damage. The proinflammatory cytokines interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNFalpha), are induced early after brain injury and have been implicated in the delayed damage. The IL-1 receptor antagonist (IL-1ra) has been shown to modulate the proinflammatory cytokine cascade by blocking the binding of IL-1 to its signaling receptor. In this study, we investigated the effect of transgenic overexpression of IL-1ra on the cytokine expression and neurological damage in a closed head injury (CHI) model of TBI. The neurological recovery, as analyzed by neurological severity score (NSS), was significantly higher in transgenic mice overexpressing the human secreted form of IL-1ra in astrocytes, directed by the murine glial fibrillary acidic protein promoter, as compared to wild-type mice. Analysis of tissue levels of cytokines by ELISA showed increased levels of TNFalpha in the cerebral cortex from the wild type mice 1 h after injury. After 4 h significant increases in the levels of IL-1beta and IL-6 were observed in the wild type mice. In the transgenic mice, on the other hand, no effect on TNFalpha levels was observed and no significant increases in IL-1beta and IL-6 levels could be detected until 6 h after injury. Thus, it can be concluded that blockage of IL-1 signaling by elevated levels of IL-1ra has a neuroprotective effect, in agreement with previous reports, and that central overexpression of IL-1ra results in delayed proinflammatory cytokine induction and improved neurological recovery after traumatic brain injury.
authors.affiliation: Department of Neurochemistry and Neurotoxicology, Stockholm University, Stockholm, Sweden.
authors.forename: Roya
authors.initials: R
authors.lastname: Tehranian
authors.forename: Siv
authors.initials: S
authors.lastname: Andell-Jonsson
authors.forename: Sara M
authors.initials: SM
authors.lastname: Beni
authors.forename: Ido
authors.initials: I
authors.lastname: Yatsiv
authors.forename: Esther
authors.initials: E
authors.lastname: Shohami
authors.forename: Tamas
authors.initials: T
authors.lastname: Bartfai
authors.forename: Johan
authors.initials: J
authors.lastname: Lundkvist
authors.forename: Kerstin
authors.initials: K
authors.lastname: Iverfeldt
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D001929:Brain Edema / Q000209:etiology; D001930:Brain Injuries / Q000150:complications / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D006624:Hippocampus / Q000293:injuries / Q000378:metabolism; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000096:biosynthesis; D015850:Interleukin-6 / Q000096:biosynthesis; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008822:Mice, Transgenic; D020127:Recovery of Function; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012795:Sialoglycoproteins / Q000096:biosynthesis*; D013997:Time Factors; D015599:Trauma Severity Indices; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: C507763:IL1RN protein, human; C507764:Il1rn protein, mouse; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D015850:Interleukin-6; D012795:Sialoglycoproteins; D014409:Tumor Necrosis Factor-alpha