Atropine-enhanced, antigen challenge-induced airway hyperreactivity in guinea pigs is mediated by eosinophils and nerve growth factor.
Although anticholinergic therapy inhibits bronchoconstriction in asthmatic patients and antigen-challenged animals, administration of atropine 1 h before antigen challenge significantly potentiates airway hyperreactivity and eosinophil activation measured 24 h later. This potentiation in airway hyperreactivity is related to increased eosinophil activation and is mediated at the level of the airway nerves. Since eosinophils produce nerve growth factor (NGF), which is known to play a role in antigen-induced airway hyperreactivity, we tested whether NGF mediates atropine-enhanced, antigen challenge-induced hyperreactivity. Antibody to NGF (Ab NGF) was administered to sensitized guinea pigs with and without atropine pretreatment (1 mg/kg iv) 1 h before challenge. At 24 h after challenge, animals were anesthetized, vagotomized, paralyzed, and ventilated. Electrical stimulation of both vagus nerves caused bronchoconstriction that was increased in challenged animals. Atropine pretreatment potentiated antigen challenge-induced hyperreactivity. Ab NGF did not affect eosinophils or inflammatory cells in any group, nor did it prevent hyperreactivity in challenged animals that were not pretreated with atropine. However, Ab NGF did prevent atropine-enhanced, antigen challenge-induced hyperreactivity and eosinophil activation (assessed by immunohistochemistry). This effect was specific to NGF, since animals given control IgG remained hyperreactive. These data suggest that anticholinergic therapy amplifies eosinophil interactions with airway nerves via NGF. Therefore, therapeutic strategies that target both eosinophil activation and NGF-mediated inflammatory processes in allergic asthma are likely to be beneficial.
Verbout
Norah G
NG
Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, 97239, USA.
Jacoby
David B
DB
Gleich
Gerald J
GJ
Fryer
Allison D
AD
D000818:Animals; D000941:Antigens / Q000276:immunology / Q000494:pharmacology*; D001249:Asthma / Q000139:chemically induced / Q000276:immunology / Q000503:physiopathology; D001285:Atropine / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D001919:Bradycardia / Q000139:chemically induced / Q000276:immunology / Q000503:physiopathology; D016535:Bronchial Hyperreactivity / Q000139:chemically induced / Q000276:immunology* / Q000503:physiopathology; D016084:Bronchoconstriction / Q000187:drug effects / Q000276:immunology; D001993:Bronchodilator Agents / Q000494:pharmacology*; D004558:Electric Stimulation; D004804:Eosinophils / Q000276:immunology*; D005260:Female; D006168:Guinea Pigs; D006339:Heart Rate / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000276:immunology; D020932:Nerve Growth Factor / Q000276:immunology / Q000378:metabolism*; D010047:Ovalbumin / Q000276:immunology / Q000494:pharmacology; D010275:Parasympathetic Nervous System / Q000276:immunology; D043585:Receptor, Muscarinic M2 / Q000502:physiology; D013047:Specific Pathogen-Free Organisms; D014628:Vagotomy; D014630:Vagus Nerve / Q000502:physiology
D000941:Antigens; D001993:Bronchodilator Agents; D043585:Receptor, Muscarinic M2; D001285:Atropine; D010047:Ovalbumin; D020932:Nerve Growth Factor