IOWA CITY, Iowa -- Human airway secretions include antimicrobial agents that normally protect the lungs from infection caused by inhaled bacteria and other microorganisms. A recent University of Iowa Health Care study suggests that high salt concentrations in the airways of people with cystic fibrosis prevent these antimicrobial factors from working effectively.
"The finding provides some new ideas about treatments for cystic fibrosis," said Sue M. Travis, Ph.D., UI research scientist and principal investigator.
Cystic fibrosis is the most common fatal inherited disease among Caucasians of Northern European descent and occurs in about one of every 2,000 births. Advances in treating the disease complications have increased the average survival age well beyond childhood; however, there is no cure.
In people with cystic fibrosis, whose lungs often become infected by inhaled microorganisms, airway antimicrobial activity has not been well understood. Previous research, including UI studies, showed that cystic fibrosis disrupts defenses against infection because the thin layer of liquid that lines the airways is saltier than in non-cystic fibrosis airways. Under normal conditions, antimicrobial peptides and proteins destroy the invasive microorganisms that land on the airway surface.
"Saltiness impairs the ability of the airway surface liquid to kill bacteria," Travis said. "We investigated specifically whether antimicrobials could kill bacteria in the salty conditions caused by cystic fibrosis."
The investigators studied how previously identified antimicrobial proteins, including lysozyme and lactoferrin, functioned in test-tube samples of human airway secretions taken from healthy people and people with cystic fibrosis.
"We found that the airway secretions, and the individual antimicrobial proteins,
could kill bacteria in low-salt conditions, but they were less able to kill
bacteria in high-salt concentrations," Travis said. "This inhibi
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Contact: Becky Soglin
becky-soglin@uiowa.edu
319-335-6660
University of Iowa
8-Sep-1999