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Estrogen May Explain Cystic Fibrosis Severity in Females

Blocks an alternate pathway to clear mucus from lungs

FRIDAY, Nov. 21 (HealthDay News) -- Estrogen blocks an alternate pathway for mucus clearance from the lungs in cystic fibrosis patients, possibly explaining why females have more severe disease and suggesting that estrogen blockers may be useful in treatment, according to a report published online Nov. 20 in the Journal of Clinical Investigation.

To investigate the known increase in cystic fibrosis disease severity in females, Ray D. Coakley, M.D., and colleagues from the University of North Carolina at Chapel Hill examined whether estrogen (17β-estradiol) affected signaling pathways in airway epithelial cells that raise intracellular calcium ion levels and stimulate chloride ion secretion in response to nucleotides. The genetic defect responsible for the disease impairs chloride ion and water secretion from airway epithelial cells, leading to mucus plugging, they note, and this alternate pathway for chloride secretion can compensate.

The researchers found reduced uridine triphosphate-mediated chloride ion secretion in both normal healthy women and women with cystic fibrosis during the periovulatory phase, when estrogen levels were highest. Estrogen also inhibited calcium ion signaling and airway surface liquid volume homeostasis in normal and cystic fibrosis airways. Estrogen antagonists such as tamoxifen prevented this inhibition of calcium ion signaling, according to the study.

"If sex hormone cycling is leading to a significant reduction in airway mucociliary clearance, perhaps low-dose oral or patch contraceptives could be modified to reduce the disadvantage," Pamela Zeitlin, M.D., from Johns Hopkins School of Medicine in Baltimore, writes in an accompanying editorial.

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