The new research findings from the University of North Carolina at Chapel Hill School of Medicine are consistent with previous UNC studies showing exposure to ozone to make asthmatics more sensitive to allergens, the environmental triggers of allergic reactions. Both ozone and endotoxin are not allergens; however, they can cause portions of the respiratory tract to become inflamed.
The study is published this week in the online December issue of the Journal of Allergy and Clinical Immunology.
Endotoxin is a complex of lipids (fats) and sugar molecules that's released through the outer cell wall of common bacteria. When the bacteria die, the cell wall collapses and endotoxin is released into the environment, finding its way into the air and dust.
"We know that asthmatics can have asthma attacks triggered by various environmental exposures, but we don't always know why certain circumstances precipitate asthma attacks when there are no clear-cut exposures to the allergens they are sensitized to," said Dr. Brian A. Boehlecke, lead author of the report, professor of medicine in UNC's pulmonary medicine division and member of UNC's Center for Environmental Medicine, Asthma and Lung Biology.
"Now it appears that various airborne irritants such as ozone and endotoxin, which can cause airway inflammation, may interact synergistically with other causes of airway problems, including allergens, to make asthma worse," he said.
The new study involved 14 participants with mild asthma for whom skin testing showed allergies to house dust mites, one of the most common airborne allergens. Study participants inhaled relatively
low levels of endotoxin over four hours that approximated those levels found in some homes and off
Contact: Leslie Lang
University of North Carolina School of Medicine