NEW YORK (Reuters Health) – The cellular response to dexamethasone is reduced in overweight/obese patients with asthma relative to their lean counterparts, according to a report in the first October issue of the American Journal of Respiratory and Critical Care Medicine.

“This study identifies what could be a significant issue for the 20 million Americans with asthma; specifically, the main controller medication might be less effective if you are overweight or obese,” lead author Dr. E. Rand Sutherland, from National Jewish Medical and Research Center in Denver, said in a statement.

The study involved 45 non-smoking adults, including 33 with asthma and 12 without. The main outcome measure was dexamethasone-induced expression of mitogen-activated protein kinase phosphatase-1 (MKP-1) in peripheral blood mononuclear cells and in bronchoalveolar lavage cells.

Dexamethasone-induced MKP-1 expression in both cell groups was significantly lower in overweight/obese asthmatics than in lean asthmatics. For example, MKP-1 expression in PBMCs increased 5.27-fold in the lean group but only 3.11-fold in the overweight group (p = 0.01).

By contrast, weight did not influence the response in subjects without asthma.

The findings also showed that baseline expression of tumor necrosis factor-alpha was directly related to body mass index.

Further research, the authors conclude, is needed to clarify the mechanisms by which an elevated body mass index blunts the response to glucocorticoids in patients with asthma.

Reference:
Am J Respir Crit Care Med 2008;178:682-687.