Severe asthma and dust mites do not mix. These microscopic arachnids promote inflammation and remodeling of the already ailing bronchi.
We do not see them, we do not feel it, but their presence strongly harms asthmatics. The mites promote remodeling of cells in the bronchi. This further aggravates the disease, concludes a team from the National Institute of Health and Medical Research (Inserm) in theAmerican Journal of Respiratory and Critical Care Medicine.
Dust mites promote asthma
In patients with severe asthma – one in ten asthma sufferers – the smooth muscle cells of the bronchi are shaped differently. Lung muscles contract more easily, while the diameter of the airways is reduced. Other studies have linked exposure to dust mites with excessive stimulation of the epithelial cells located on the lining of the bronchi. In response, they secrete factors involved in inflammation, which triggers an asthma attack.
The Inserm unit at the Cardio-Thoracic Research Center in Bordeaux (Gironde) establishes a bridge between these medical observations. The researchers used epithelial cells and smooth muscle cells from two types of subjects: severe asthma, or healthy. Placed in culture, these cells were brought into contact with mites.
A chain reaction
In the presence of micro-arachnids, epithelial cells from asthma patients become activated. They release leukotrienes, factors of inflammation. Smooth muscle cells, which overexpress receptors for this factor, intercept them. They remodel, which results in worsening asthma. “Mites are not the cause of everything”, tempers Patrick Berger, co-author of the study. “It is clearly shown that the smooth muscle cells of severe asthma patients are already remodeled in the absence of these microarachnids. But this work shows that mites represent an additional contribution to remodeling. “
Like allergy sufferers, asthmatics would therefore benefit from anticipating this type of complication by avoiding carpets and double curtains and by using dust mite covers on the bedding. There is also a drug that targets leukotriene receptors. But the montelukast (Kastlutemon and generics) is recommended for mild asthma only. No study has proven in humans that it prevents smooth muscle cells from reshaping.
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