title: TNF alpha reduces tachykinin, PGE2-dependent, relaxation of the cultured mouse trachea by increasing the activity of COX-2.
abstract: 1. Chronic inflammation is a central feature of asthma. The inflammatory cytokine tumour necrosis factor alpha (TNFalpha) has been implicated in this disease, and is known to alter airway smooth muscle functionally. 2. The aim of this study was to investigate the influence of TNFalpha on tachykinin-induced airway relaxation. Mouse tracheae were cultured in the absence and presence of TNFalpha for 1 or 4 days. 3. In the absence of TNFalpha, substance P (SP) and neurokinin A (NKA) induced comparable levels of relaxation in fresh and cultured segments. Functional studies with selective antagonists/inhibitors indicated that the relaxation was mediated by the NK(1) receptor coupled to cyclooxygenase (COX)-2 activation and subsequent release of prostaglandin E(2) (PGE(2)). TNFalpha attenuated SP- and NKA-induced relaxation in a time- and concentration-dependent manner, decreasing the ability of PGE(2) to relax tissues. 4. Further studies indicated that TNFalpha elevated COX-2 activity and that concomitant inhibition of COX-2 reversed TNFalpha-attenuated PGE(2) relaxation. Culture with PGE(2) decreased SP- and PGE(2)-mediated relaxation, further implicating the activity of COX-2 in the attenuation of tachykinin signalling. 5. Gene expression analysis demonstrated that TNFalpha increased the expression of smooth muscle COX-2, PGE(2) synthase and EP(2) receptor mRNA, and decreased the expression of the EP(4) receptor. 6. Overall, these results show that NK(1) receptor-mediated relaxation induced by PGE(2) is attenuated by prolonged TNFalpha stimulation. Increased COX-2 activity induced by TNFalpha appears to be central to this process.
authors.affiliation: Laboratory of Clinical and Experimental Allergy Research, Department of Otorhinolaryngology, Malmö University Hospital, Malmö SE-20502, Sweden.
authors.forename: Ofir
authors.initials: O
authors.lastname: Bachar
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Rose
authors.forename: Mikael
authors.initials: M
authors.lastname: Adner
authors.forename: Xudong
authors.initials: X
authors.lastname: Wang
authors.forename: Clodagh E
authors.initials: CE
authors.lastname: Prendergast
authors.forename: Ashley
authors.initials: A
authors.lastname: Kempf
authors.forename: Nigel P
authors.initials: NP
authors.lastname: Shankley
authors.forename: Lars-Olaf
authors.initials: LO
authors.lastname: Cardell
mesh_terms: D000818:Animals; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000037:antagonists & inhibitors / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D018040:Receptors, Neurokinin-1 / Q000819:agonists / Q000378:metabolism; D015320:Tachykinins / Q000037:antagonists & inhibitors / Q000502:physiology*; D014132:Trachea / Q000187:drug effects / Q000201:enzymology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D018040:Receptors, Neurokinin-1; D015320:Tachykinins; D014409:Tumor Necrosis Factor-alpha; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone