SELECTED ARTICLES FROM THE RECENT LITERATURE 2008

4/23/2008

Pulmonary Inflammation Persists After Cessation of Exposure to Toluene Diisocyanate

Summary
The authors' goal was to see if pulmonary inflammatory findings persisted in patients with occupational asthma due to toluene diisocyanate exposure after cessation of such exposure. They studied 17 patients after the initiation of inhaled steroids and cessation of workplace exposure. They looked at indices of bronchial inflammation as well as lung function. Bronchoscopy was performed on these patients two days after a positive inhalation challenge test after which budesonide at 1600 mcg a day was started. Bronchoscopy, spirometry, and histamine challenge tests were repeated at six months, and on an average every three years. Fifteen healthy subjects served as controls.

Although bronchial hyperreactivity diminished over time, the forced expiratory volume at 1 second and forced vital capacity continued to decline. There was a median yearly reduction in FEV1 of 79 ml. IL-4 levels in bronchial mucosa were elevated for a year and then declined.

IL-6, IL-15, and tumor necrosis factor alpha messenger-RNA were higher in hyperreactive patients than in non-hyperreactive patients at the end of follow-up.

The authors concluded that inflammation can persist in diisocyanate-induced asthma in spite of the fact that workplace exposure was ceased and inhaled corticosteroid therapy was instituted. Persistent nonspecific bronchial hyperreactivity was associated with the presence of proinflammatory cytokines that were produced mainly by macrophages.

Reference
Piirila PL, et al. Inflammation and functional outcome in diisocyanate induced asthma after cessation of exposure. Allergy 2008; 63(5):583-591.

 

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