Macrophage TNF-α mediates parathion-induced airway hyperreactivity in guinea pigs

Am J Physiol Lung Cell Mol Physiol. 2013 Apr 15;304(8):L519-29. doi: 10.1152/ajplung.00381.2012. Epub 2013 Feb 1.


Organophosphorus pesticides (OPs) are implicated in human asthma. We previously demonstrated that, at concentrations that do not inhibit acetylcholinesterase activity, the OP parathion causes airway hyperreactivity in guinea pigs as a result of functional loss of inhibitory M2 muscarinic receptors on parasympathetic nerves. Because macrophages are associated with asthma, we investigated whether macrophages mediate parathion-induced M2 receptor dysfunction and airway hyperreactivity. Airway physiology was measured in guinea pigs 24 h after a subcutaneous injection of parathion. Pretreatment with liposome-encapsulated clodronate induced alveolar macrophage apoptosis and prevented parathion-induced airway hyperreactivity in response to electrical stimulation of the vagus nerves. As determined by qPCR, TNF-α and IL-1β mRNA levels were increased in alveolar macrophages isolated from parathion-treated guinea pigs. Parathion treatment of alveolar macrophages ex vivo did not significantly increase IL-1β and TNF-α mRNA but did significantly increase TNF-α protein release. Consistent with these data, pretreatment with the TNF-α inhibitor etanercept but not the IL-1β receptor inhibitor anakinra prevented parathion-induced airway hyperreactivity and protected M2 receptor function. These data suggest a novel mechanism of OP-induced airway hyperreactivity in which low-level parathion activates macrophages to release TNF-α-causing M2 receptor dysfunction and airway hyperreactivity. These observations have important implications regarding therapeutic approaches for treating respiratory disease associated with OP exposures.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Bronchial Hyperreactivity / chemically induced*
  • Bronchial Hyperreactivity / genetics
  • Bronchial Hyperreactivity / immunology*
  • Bronchial Hyperreactivity / pathology
  • Clodronic Acid / pharmacology
  • Etanercept
  • Female
  • Guinea Pigs
  • Humans
  • Immunoglobulin G / pharmacology
  • Insecticides / toxicity
  • Interleukin 1 Receptor Antagonist Protein / pharmacology
  • Interleukin-1beta / antagonists & inhibitors
  • Interleukin-1beta / genetics
  • Interleukin-1beta / metabolism
  • Macrophage Activation / drug effects
  • Macrophages, Alveolar / drug effects*
  • Macrophages, Alveolar / immunology*
  • Macrophages, Alveolar / pathology
  • Parathion / toxicity*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Receptor, Muscarinic M2 / agonists
  • Receptor, Muscarinic M2 / antagonists & inhibitors
  • Receptors, Tumor Necrosis Factor
  • Tumor Necrosis Factor-alpha / antagonists & inhibitors
  • Tumor Necrosis Factor-alpha / genetics
  • Tumor Necrosis Factor-alpha / immunology*


  • Immunoglobulin G
  • Insecticides
  • Interleukin 1 Receptor Antagonist Protein
  • Interleukin-1beta
  • RNA, Messenger
  • Receptor, Muscarinic M2
  • Receptors, Tumor Necrosis Factor
  • Tumor Necrosis Factor-alpha
  • Clodronic Acid
  • Parathion
  • Etanercept