Two teams of medical researchers have identified what they believe is a simple, effective and inexpensive treatment to reduce lung problems associated with cystic fibrosis, the leading fatal genetic illness among whites.
The new therapy also appears to be safe and easy to take.

By inhaling a saltwater aerosol solution almost twice as salty as the Atlantic Ocean for between 10 and 15 minutes at least twice a day, young patients should be able to avoid a significant part of the damage the disease causes to their lungs, the researchers said. That's because the aerosolized saltwater restores the thin lubricant layer of water that normally coats airway surfaces. This water layer promotes the clearance of the naturally occurring mucus the body uses to trap harmful bacteria, viruses and other foreign particles.

One team consists of researchers at the University of North Carolina at Chapel Hill School of Medicine and UNC Hospitals. The other includes researchers at the Royal Prince Alfred Hospital, the University of Sydney and the Woolcock Institute of Medical Research, all in Sydney.

Reports on both studies, which were collaborative and complementary, appear in the New England Journal of Medicine.

Cystic fibrosis appears on average in one of four children of parents who both carry a defective copy of a gene known as CFTR, Scott H.Donaldson said.
Children born with the disease soon develop chronic lung damage, since their lungs cannot clear excessively sticky mucus by sweeping it to the mouth, where it is swallowed and eliminated. Respiratory failure is the leading cause of death in cystic fibrosis patients.

This research is important both for its immediate application and because it provides the roadmap for development of future effective therapies for cystic fibrosis, Richard C.Boucher said.
This study appears to establish the concept that the surfaces of the lungs of cystic fibrosis patients are dehydrated, and restoring hydration with hypertonic saline treats the basic cause of this disease.

In healthy people, a thin film of water only five-to-10 microns thick coats and lubricates the open areas of the lungs, Boucher said. "Our studies demonstrate that cystic fibrosis lungs are missing this watery layer, and, hence, to treat the disease effectively, you have to re-hydrate cystic fibrosis airway surfaces. This can be done with inhaled water solutions that are seven or eight times more salty than blood or about three-quarters as salty as the Dead Sea.

" Salt essentially sucks water from the lung tissues out onto the airways. The irony is that the therapy works better in cystic fibrosis subjects than non-cystic fibrosis subjects," Boucher added.

The UNC study involved 24 cystic fibrosis patients who each inhaled the salt solution with or without pretreatment with a compound known as Amiloride over two-week periods.
Analysis of mucus clearance and lung function showed that the high-salt aerosol alone worked best, which somewhat surprised the medical scientists.
Laboratory studies established that the failure of Amiloride to promote the effect of hypertonic saline reflected a novel action of the drug – i.e., to block water transport. This novel observation in part established hydration of airway surfaces as the mechanism of action for hypertonic saline.

Following communication with the UNC group, the Australian researchers used a comparable protocol to study another 164 patients for a longer period, almost a year.
During the longer span, the Sydney researchers also found fewer lung problems with the concentrated saline than with normal saline, less need for antibiotics to treat lung infections over time, and improved attendance by patients at school, work and other activities during the 48 weeks.

Because salt solutions are so cheap to make, another attractive aspect of this new therapy is that its clinical benefits will come at a minimal treatment expense, in contrast to many other available therapies, Donaldson said.

Source: University of North Carolina School of Medicine, 2006


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