title: Treatment of neuroinflammation by soluble tumor necrosis factor receptor Type II fused to a thermally responsive carrier.
abstract: OBJECTIVE
  Biochemical irritation of the dorsal root ganglion (DRG) after intervertebral disc herniation contributes to radiculopathy through tumor necrosis factor-alpha (TNFalpha)-mediated inflammation. Soluble TNF receptor Type II (sTNFRII) sequesters this cytokine, providing clinical benefit. Previous work involving conjugation of sTNFRII with thermally responsive elastin-like polypeptide (ELP) yielded a chimeric protein (ELP-sTNFRII) with in vitro anti-TNFalpha bioactivity. Furthermore, temperature-triggered ELP aggregation into a "depot" prolongs protein residence time following perineural injection. In this study the authors evaluated the inflammatory phenotype of DRG explants after TNFalpha stimulation, and assessed the abilities of sTNFRII or ELP-sTNFRII to attenuate these neuro-inflammatory changes.
  
  
  METHODS
  Rat lumbar DRGs (35 animals) were treated in 6 groups, as follows: control; TNFalpha (25 ng/ml); TNFalpha with low-(0.2 microg/ml) or high-dose (1 microg/ml) sTNFRII; and TNFalpha with low-(52.5 microg/ml) or high-dose (262.5 microg/ml) ELP-sTNFRII. After 24 hours, supernatant was evaluated for inflammatory cytokines (interleukin [IL]-1, IL-6, and IL-10); prostaglandin E2; and metabolites (glutamate, lactate, and pyruvate). Single-factor analysis of variance with post hoc Dunn analysis (alpha = 0.05) was used to assess treatment differences.
  
  
  RESULTS
  Incubation of explants with TNFalpha caused metabolic stress reflected by an increased lactate/pyruvate ratio (1.8 +/- 0.5-fold) and extracellular glutamate (79 +/- 8% increase). Inflammatory activation was observed with heightened IL-6 release (5.2 +/- 1.4-fold) and prostaglandin E2 production (14 +/- 3-fold). An autoregulatory response occurred with an 11.8 +/- 0.6-fold increase in sTNFRI shedding. Treatment with high doses of sTNFRII or ELP-sTNFRII reversed all changes. Values are expressed as the mean +/- standard deviation.
  
  
  CONCLUSIONS
  These results demonstrate that TNFalpha stimulation of DRG explants yields a phenotype of neurotoxic metabolite release and inflammatory mediator expression. Coincubation with either sTNFRII or ELP-sTNFRII antagonizes TNFalpha activity to abrogate these changes, suggesting potential for therapeutic intervention to treat peripheral nerve inflammatory disease.
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA.
authors.forename: Mohammed F
authors.initials: MF
authors.lastname: Shamji
authors.forename: Liufang
authors.initials: L
authors.lastname: Jing
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
authors.forename: Priscilla
authors.initials: P
authors.lastname: Hwang
authors.forename: Odelia
authors.initials: O
authors.lastname: Ghodsizadeh
authors.forename: Allan H
authors.initials: AH
authors.lastname: Friedman
authors.forename: William J
authors.initials: WJ
authors.lastname: Richardson
authors.forename: Lori A
authors.initials: LA
authors.lastname: Setton