ATS: Vitamin D May Inhibit Airway Remodeling in Asthma

University of Pennsylvania researchers plan clinical trial of Vitamin D therapy over the next year

THURSDAY, May 21 (HealthDay News) -- Vitamin D may inhibit the proliferation of human airway smooth muscle (HASM) that is characteristic of the airway remodeling that leads to difficulty breathing in asthma and chronic obstructive pulmonary disease (COPD), according to a poster presented at the annual meeting of the American Thoracic Society, held from May 15 to 20 in San Diego.

Gautam Damera, Ph.D, of the University of Pennsylvania in Philadelphia, and colleagues used cells sampled from airways of 12 subjects with and without asthma to compare the inhibitory effect of vitamin D (calcitriol) and the corticosteroid dexmethasone on HASM proliferation. In parallel experiments, the researchers investigated the mechanism of action of calcitriol by examining its effect on the expression of key proteins in HASM cell growth.

The researchers found that calcitriol inhibited HASM in a dose-dependent manner with a maximum inhibitory effect of 60 percent (± 3 percent) at a dose of 100 nM, while dexmethasone showed no effect on HASM cell growth. In parallel experiments, the researchers determined that calcitriol inhibits platelet-derived growth factor-induced HASM cell growth by preventing activation of key proteins responsible for cell-cycle progression.

"These data suggest that calcitriol uniquely inhibits platelet-derived growth factor-induced HASM cell growth by inhibiting signaling pathways downstream from cyclin D expression but upstream from retinoblastoma phosphorylation. Taken together, calcitriol may offer a unique therapeutic approach in the management of diseases characterized by increased airway smooth muscle mass that include asthma and COPD," the authors write.

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