title: Effect of endogenous nitric oxide on tumour necrosis factor-alpha-induced leukosequestration and IL-8 release in guinea-pigs airways in vivo.
abstract: 1. Tumour necrosis factor-alpha (TNF-alpha) is implicated in the pathogenesis of many pulmonary and airway diseases. TNF-alpha stimulation may release interleukin-8 (IL-8) in airways mediated via an increase in intracellular oxidant stress. In the present study, we have assessed leukosequestration and IL-8 release in the airways in response to intratracheal administration of human recombinant TNF-alpha, and examined the modulatory role of endogenous NO by pretreatment with a NO synthase inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME). 2. TNF-alpha (10(2)-10(-4) u) was administered intratracheally in male guinea-pigs which were anaesthetized with urethane and were ventilated artificially. TNF-alpha induced a time- and dose-related increase in neutrophil numbers and a concomitant increase in human IL-8 equivalent level retrieved from bronchoalveolar lavage (BAL) with the peak effect at 10(3) u at 6 h of TNF-alpha injection (late phase). Intratracheal administration of recombinant human (rh)IL-8 (0.025, 0.25, 2.5 ng) producing a similar range of human IL-8 equivalent levels in BAL as measured in our results induced neutrophil recovery in BAL fluid to a similar extent. Administration of anti-IL-8 antibody prevented the late phase of neutrophil recruitment induced by TNF-alpha or rhIL-8. 3. Pretreatment with L-NAME significantly enhanced the TNF-alpha (10(3) u)-induced neutrophil recruitment and human IL-8 equivalents production at 6 h, but not at 1 h of TNF-alpha administration (early phase). L-Arginine reversed the responses to L-NAME. Pretreatment with 0.2% DMSO (i.v.) significantly inhibited TNF-alpha-induced neutrophil recruitment and human IL-8 equivalents release both in the early and late phase of the responses. Pretreatment with DMSO also inhibited the enhancement effect of L-NAME on the late phase of TNF-alpha-induced responses. DMSO failed to modify exogenous rhIL-8-induced neutrophil recruitment. Neither L-NAME nor DMSO alone induced any significant change in neutrophil numbers or human IL-8 equivalent level in BAL fluid. 4. Neutrophil depletion by cyclophosphamide pretreatment failed to modify TNF-alpha-induced human IL-8 equivalent release. 5. The expression of beta 2-integrin, CD11b/CD18 on neutrophils was increased only in the late but not early phase of TNF-alpha stimulation. L-NAME failed to modify these responses. 6. In conclusion, we demonstrated that NO may be an important endogenous inhibitor of TNF-alpha-induced leukocyte chemotaxis via inhibition of IL-8 production. Thus, the production of NO in airway inflammatory diseases may play a negative feedback role in self-limiting the magnitude of inflammatory responses.
authors.affiliation: Department of Thoracic Medicine, Chang Gung Memorial Hospital, Taipei, Taiwan.
authors.forename: H P
authors.initials: HP
authors.lastname: Kuo
authors.forename: K H
authors.initials: KH
authors.lastname: Hwang
authors.forename: H C
authors.initials: HC
authors.lastname: Lin
authors.forename: C H
authors.initials: CH
authors.lastname: Wang
authors.forename: L C
authors.initials: LC
authors.lastname: Lu
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D018821:CD18 Antigens / Q000096:biosynthesis; D003520:Cyclophosphamide / Q000494:pharmacology; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006168:Guinea Pigs; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D016209:Interleukin-8 / Q000378:metabolism*; D016177:Macrophage-1 Antigen / Q000096:biosynthesis; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D011994:Recombinant Proteins / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects* / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000494:pharmacology*
chemical_list: D018821:CD18 Antigens; D004791:Enzyme Inhibitors; D007166:Immunosuppressive Agents; D016209:Interleukin-8; D016177:Macrophage-1 Antigen; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D003520:Cyclophosphamide; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester