ATS: Dietary Fat, Sex Hormones Affect Airway Inflammation
Researchers shed light on how the presence of fat suppresses and estrogen increases bronchodilation
MONDAY, May 17 (HealthDay News) -- A high fat intake can increase airway inflammation and suppress bronchodilator response in people with asthma, but a concentration of estrogens may facilitate bronchodilation, and activation of estrogen receptors may be therapeutic for airway diseases, according to two studies presented at the annual meeting of the American Thoracic Society, held from May 14 to 19 in New Orleans.
Lisa G. Wood, Ph.D., of the University of Newcastle in Australia, and colleagues gave 16 obese subjects with asthma a high-fat/high-energy (HF) food challenge and randomized 30 non-obese subjects with asthma to receive the HF or a low-fat/low-energy (LF) food challenge. Four hours after eating, the HF subjects had a significantly higher increase in sputum neutrophils (16.4 versus 3.4 percent) and an impaired bronchodilator response compared to the LF subjects. There was no difference in the response to the HF challenge between obese subjects and non-obese subjects with asthma.
Elizabeth A. Townsend, of the Mayo Clinic College of Medicine in Rochester, Minn., and colleagues hypothesized that estrogens facilitate bronchodilation by modulating cyclic nucleotide regulation. Examining surgical lung samples of human airway smooth muscle (ASM), they found expression of both estrogen receptors ERα and ERβ. In ASM cells loaded with the Ca2+ indicator fura-2, acute exposure to 17β estradiol blunted response to bronchoconstrictor agonists, and these effects were prevented by ER antagonists.
"These novel data suggest that, in human ASM, clinically-relevant concentrations of estrogens act via ERs and the cAMP pathway to non-genomically produce bronchodilation. Activation of ERs may be a novel therapeutic mechanism in airway diseases such as asthma, especially in combination with established therapies such as β2-agonists which also act via cAMP," Townsend and colleagues conclude.