title: Tumor necrosis factor alpha and interleukin-1beta stimulate the expression of cyclooxygenase II but do not alter prostaglandin E2 receptor mRNA levels in cultured dorsal root ganglia cells.
abstract: Tumor necrosis factor alpha (TNFalpha) and interleukin 1beta (IL-1beta) are pro-inflammatory cytokines capable of altering the sensitivity of sensory neurons. Because sensitization elicited by IL-1beta and TNFalpha is blocked by inhibition of the inducible enzyme, cyclooxygenase-II (COX-2), we examined whether these cytokines could increase COX-2 expression in dorsal root ganglion (DRG) cultures. Treatment of cell cultures with either IL-1beta or TNFalpha increases immunoreactive COX-2, as measured by immunoblotting, in a time- and concentration-dependent manner. A 24-h pretreatment with 10 ng/ml IL-1beta or 50 ng/ml TNFalpha augmented COX-2 expression 50- and 8-fold over basal levels, respectively. Immunohistochemistry established the presence of COX-2-like immunoreactivity in both neuronal and non-neuronal cells in culture. The addition of IL-1 receptor antagonist blocked the induction of COX-2 expression by IL-1beta, but did not alter TNFalpha-stimulated increases in COX-2, indicating that the mechanism of TNFalpha is not limited to increasing the expression of IL-1beta. The basal and TNFalpha-induced expression of COX-2 was not dependent on the presence of NGF in the growth media. IL-1beta and TNFalpha treatment for 24 h enhanced prostaglandin E2 (PGE2) production 2-4-fold, which was blocked by pretreatment with the COX-2 inhibitor, NS-398. Exposing cultures to PGE2, IL-1beta, or TNFalpha for 24 h did not alter PGE2 receptor (EP) mRNA levels. These results indicate that TNFalpha and IL-1beta induce the functional expression of COX-2 but not EP receptors in DRG cells in culture and suggest that cytokine-induced sensitization of sensory neurons is secondary to prostaglandin production and not alterations in EP receptors.
authors.affiliation: Department of Pharmacology and Toxicology, Indiana University School of Medicine, Medical Science Bldg-MS A401, 635 Barnhill Drive, Indianapolis, IN 46202, USA.
authors.forename: Jill C
authors.initials: JC
authors.lastname: Fehrenbacher
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Burkey
authors.forename: Grant D
authors.initials: GD
authors.lastname: Nicol
authors.forename: Michael R
authors.initials: MR
authors.lastname: Vasko
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western / Q000379:methods; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005455:Fluorescent Antibody Technique / Q000379:methods; D005727:Ganglia, Spinal / Q000166:cytology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D007124:Immunoenzyme Techniques / Q000379:methods; D007375:Interleukin-1 / Q000494:pharmacology*; D008297:Male; D009457:Neuroglia / Q000187:drug effects; D009474:Neurons / Q000187:drug effects*; D009578:Nitrobenzenes / Q000494:pharmacology; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018078:Receptors, Prostaglandin E / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013449:Sulfonamides / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D016861:Cyclooxygenase Inhibitors; D007375:Interleukin-1; D009578:Nitrobenzenes; D012333:RNA, Messenger; D018078:Receptors, Prostaglandin E; D013449:Sulfonamides; D014409:Tumor Necrosis Factor-alpha; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C489691:Ptgs2 protein, rat