title: TNF-alpha neutralizing antibody blocks thermal sensitivity induced by compound 48/80-provoked mast cell degranulation.
abstract: BACKGROUND
  Neuro-inflammatory circuits in the tissue regulate the complex pathophysiology of pain. Protective nociceptive pain serves as an early warning system against noxious environmental stimuli. Tissue-resident mast cells orchestrate the increased thermal sensitivity following injection of basic secretagogue compound 48/80 in the hind paw tissues of ND4 mice. Here we investigated the effects of pre-treatment with TNF-α neutralizing antibody on compound 48/80-provoked thermal hyperalgesia.
  
  
  METHODS
  We treated ND4 Swiss male mice with intravenous anti-TNF-α antibody or vehicle 30 minutes prior to bilateral, intra-plantar compound 48/80 administration and measured changes in the timing of hind paw withdrawal observed subsequent to mice being placed on a 51oC hotplate. We also assessed changes in tissue swelling, TNF-α gene expression and protein abundance, mast cell degranulation, and neutrophil influx in the hind paw tissue.
  
  
  RESULTS
  We found that TNF-α neutralization significantly blocked thermal hyperalgesia, and reduced early tissue swelling. TNF-α neutralization had no significant effect on mast cell degranulation or neutrophil influx into the tissue, however. Moreover, no changes in TNF-α protein or mRNA levels were detected within 3 hours of administration of compound 48/80.
  
  
  CONCLUSIONS
  The neutralizing antibodies likely target pre-formed TNF-α including that stored in the granules of tissue-resident mast cells. Pre-formed TNF-α, released upon degranulation, has immediate effects on nociceptive signaling prior to the induction of neutrophil influx. These early effects on nociceptors are abrogated by TNF-α blockade, resulting in compromised nociceptive withdrawal responses to acute, harmful environmental stimuli.
authors.affiliation: Biology Department, Macalester College, St. Paul, MN 55015, USA.
authors.forename: Devavani
authors.initials: D
authors.lastname: Chatterjea
authors.affiliation: Biology Department, Macalester College, St. Paul, MN 55015, USA.
authors.forename: Luisa
authors.initials: L
authors.lastname: Paredes
authors.affiliation: Biology Department, Macalester College, St. Paul, MN 55015, USA.
authors.forename: Tijana
authors.initials: T
authors.lastname: Martinov
authors.affiliation: Biology Department, Macalester College, St. Paul, MN 55015, USA.
authors.forename: Evelyn
authors.initials: E
authors.lastname: Balsells
authors.affiliation: Biology Department, Macalester College, St. Paul, MN 55015, USA.
authors.forename: Juliann
authors.initials: J
authors.lastname: Allen
authors.affiliation: Biology Department, Macalester College, St. Paul, MN 55015, USA.
authors.forename: Akilah
authors.initials: A
authors.lastname: Sykes
authors.affiliation: Biology Department, Macalester College, St. Paul, MN 55015, USA.
authors.forename: Alyssa
authors.initials: A
authors.lastname: Ashbaugh