title: Toll-like receptor 4/nuclear factor-kappa B signaling detected in brain after early subarachnoid hemorrhage.
abstract: BACKGROUND
  Inflammation and immunity play a vital role in the pathogenesis of early brain injury after subarachnoid hemorrhage (SAH). Nuclear factor-kappa B (NF-kappaB) regulates many genes essential for inflammation and immunity and is activated by toll-like receptor (TLR). This study aimed to detect the expression of the toll-like receptor 4/nuclear factor-kappa B (TLR4/NF-kappaB) signaling in the rat brain after early SAH.
  
  
  METHODS
  The rats were decapitated and their brains were removed at 0, 2, 4, 6, 12, 24 and 48 hours after a single injection of blood into the prechiasmatic cistern. mRNA expression of TLR4 was measured by Taqman real-time RT-PCR, and protein expression by immunohistochemistry and Western blotting. NF-kappaB activity and concentrations of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) were measured by enzyme-linked immunosorbent assay (ELISA).
  
  
  RESULTS
  TaqMan real-time RT-PCR and Western blotting identified a biphasic change in TLR4 expression in both mRNA and protein: an initial peak (2 - 6 hours) and a sustained elevation (12 - 48 hours). Immunohistochemical staining showed the inducible expression of TLR4-like immunoreactions predominantly in glial cells and vascular endothelium. A similar biphasic change in the activation of NF-kappaB subunit p65 as well as the production of NF-kappaB-regulated proinflammatory cytokines (TNF-alpha, IL-1beta and IL-6) were detected by ELISA.
  
  
  CONCLUSIONS
  These data suggest that experimental SAH induces significant up-regulation of TLR4 expression and the NF-kappaB signaling in early brain injury. Activation of the TLR4/NF-kappaB signaling may regulate the inflammatory responses after SAH.
authors.affiliation: Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China.
authors.forename: Chun-xiao
authors.initials: CX
authors.lastname: Ma
authors.forename: Wei-ning
authors.initials: WN
authors.lastname: Yin
authors.forename: Bo-wen
authors.initials: BW
authors.lastname: Cai
authors.forename: Jian
authors.initials: J
authors.lastname: Wu
authors.forename: Jun-yi
authors.initials: JY
authors.lastname: Wang
authors.forename: Min
authors.initials: M
authors.lastname: He
authors.forename: Hong
authors.initials: H
authors.lastname: Sun
authors.forename: Jun-li
authors.initials: JL
authors.lastname: Ding
authors.forename: Chao
authors.initials: C
authors.lastname: You
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D016207:Cytokines / Q000032:analysis; D008297:Male; D016328:NF-kappa B / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology*; D013345:Subarachnoid Hemorrhage / Q000276:immunology* / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000032:analysis / Q000235:genetics / Q000502:physiology*
chemical_list: D016207:Cytokines; D016328:NF-kappa B; D012333:RNA, Messenger; C495347:Tlr4 protein, rat; D051197:Toll-Like Receptor 4