title: Inhibition of interleukin-6 trans-signaling in the brain facilitates recovery from lipopolysaccharide-induced sickness behavior.
abstract: BACKGROUND
  Interleukin (IL)-6 is produced in the brain during peripheral infection and plays an important but poorly understood role in sickness behavior. Therefore, this study investigated the capacity of soluble gp130 (sgp130), a natural inhibitor of the IL-6 trans-signaling pathway to regulate IL-6 production in microglia and neurons in vitro and its effects on lipopolysaccharide (LPS)-induced sickness behavior in vivo.
  
  
  METHODS
  A murine microglia (BV.2) and neuronal cell line (Neuro.2A) were used to study the effects of stimulating and inhibiting the IL-6 signaling pathway in vitro. In vivo, adult (3-6 mo) BALB/c mice received an intracerebroventricular (ICV) injection of sgp130 followed by an intraperitoneal (i.p.) injection of LPS, and sickness behavior and markers of neuroinflammation were measured.
  
  
  RESULTS
  Soluble gp130 attenuated IL-6- and LPS-stimulated IL-6 receptor (IL-6R) activation along with IL-6 protein release in both microglial (BV.2) and neuronal (Neuro.2A) cell types in vitro. Moreover, in vivo experiments showed that sgp130 facilitated recovery from LPS-induced sickness, and this sgp130-associated recovery was paralleled by reduced IL-6 receptor signaling, mRNA, and protein levels of IL-6 in the hippocampus.
  
  
  CONCLUSIONS
  Taken together, the results show that sgp130 may exert an anti-inflammatory effect on microglia and neurons by inhibiting IL-6 binding. These data indicate that sgp130 inhibits the LPS-induced IL-6 trans-signal and show IL-6 and its receptor are involved in maintaining sickness behavior.
authors: Laboratory of Integrative Immunology and Behavior, Animal Science Department, University of Illinois at Urbana-Champaign, Urbana, 7 Animal Sciences Lab 1207 W, Gregory Dr, Urbana, IL 61801, USA.
authors: Michael D
authors: MD
authors: Burton
authors: Nathan L
authors: NL
authors: Sparkman
authors: Rodney W
authors: RW
authors: Johnson
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