Mild asthma in overweight women ‘a distinct phenotype’
MedWire News: Mild asthma in overweight women may be a distinct phenotype of the respiratory condition, say Pascal Chanez (Université de la Méditerranée, Marseille, France) and colleagues.
Previous studies have shown that there is a significant association between obesity and the development of asthma, with both conditions linked to systemic inflammation, explain the researchers.
However, they add that “the relation between a higher body mass index and bronchial hyper-responsiveness (BHR), an important feature of asthma, remains controversial.”
The researchers studied 19 overweight (body mass index [BMI] more than 25 kg/m2) women with asthma and 11 normal-weight (BMI 25 kg/m2 or less) women with the respiratory condition who were aged between 40 and 65 years.
All the participants, who had well-controlled asthma, underwent bronchial challenge tests with methacholine and adenosine monophosphate (AMP).
The researchers explain that methacholine causes airflow limitation predominantly via a direct effect on the airway smooth muscle without intervening pathways, whereas AMP is an indirect stimulant that binds to “primed” mast cells leading to degranulation and the release of pro-inflammatory mediators.
The participants also supplied blood samples for assessment of blood inflammatory markers (leptin and high sensitivity C-reactive protein [hs-CRP]), as well as completing the Borg scale for perception of dyspnea.
The researchers found that overweight patients had a significantly lower dose-response slope to methacholine challenge than normal-weight patients. However, there was no significant difference between the groups regarding response to AMP challenge.
Furthermore, leptin and hs-CRP levels were higher in overweight than normal-weight patients, at 35.25 versus 13.48 μg/l and 6.54 versus 5.15 mg/ml, respectively, and overweight patients had higher baseline perception scores for dyspnea than their normal-weight counterparts.
Chanez and team conclude in the journal Respiratory Medicine: “Our findings suggest that overweight asthmatic women do not feature increased airway inflammation, but do represent a distinct phenotype as compared to normal weight patients.”
They add: “These findings could be relevant for tailored asthma management.”
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By Mark Cowen