FcεRI expression increased in airways of fatal asthma attack patients
: Expression of the high-affinity immunoglobulin (Ig)E receptor (FcεRI) is increased in the small and large airways of patients who have suffered a fatal asthma (FA) attack, researchers have found.
Targeting the activation of FcεRI may therefore reduce IgE-mediated inflammatory reactions, as well as airway remodeling and destruction, in patients with asthma, says the team.
Writing in the journal Clinical and Experimental Allergy, I Den Otter (Leiden University Medical Center, The Netherlands) and team explain: "IgE and its high-affinity receptor FcεRI play an important role in allergy and asthma. The distribution of FcεRI expression in the airways and within the airway wall, however, is largely unknown."
To investigate, the researchers studied postmortem tissue samples taken from the small (SA) and large (LA) airways of 24 non-smokers and 13 smokers with FA, and from 19 patients who died of non-pulmonary causes (controls).
Immunohistochemical staining was used to assess expression of FcεRI and mast cell tryptase marker AA1 in the inner and outer layers of both SA and LA.
The researchers found that FcεRI expression was higher in the inner and outer layers of SA tissue taken from non-smokers and smokers with FA compared with SA tissue from controls.
FcεRI expression was higher in the outer layer of LA tissue from non-smokers with FA only, compared with that from controls.
The researchers also found that AA1 expression was higher in the outer layer of SA tissue from non-smokers with FA compared with that from smokers with FA and controls, and this correlated with FcεRI expression in this layer, they note.
Den Otter and team write: "Our findings on the expression of FcεRI in the SA imply that the IgE-mediated reactions against allergens might also occur at this location, besides the well-established reaction in LA."
They conclude: "Inflammation caused by IgE-mediated reactions in SA might contribute to tissue destruction and airway remodeling, which could lead to small airways dysfunction. Therefore, targeting the activation of FcεRI to treat asthma might dampen IgE-mediated inflammatory reactions and its downstream processes such as airway remodeling in both LA and SA."
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By Mark Cowen