Asthma exacerbations are triggered by rhinovirus infections. We employed a systems biology approach to delineate upper-airway gene network patterns underlying asthma exacerbation phenotypes in children. Cluster analysis unveiled distinct IRF7 hi versus IRF7 lo molecular phenotypes, the former exhibiting robust upregulation of Th1/type I IFN responses and the latter an alternative signature marked by upregulation of cytokine and growth factor signaling and downregulation of IFN-g. The two phenotypes also produced distinct clinical phenotypes. For IRF7 lo children, symptom duration prior to hospital presentation was more than twice as long from initial symptoms (p = 0.011) and nearly three times as long for cough (p < 0.001), the odds ratio of admission to hospital was increased more than 4-fold (p = 0.018), and time to recurrence was shorter (p = 0.015). In summary, our findings demonstrate that asthma exacerbations in children can be divided into IRF7 hi versus IRF7 lo phenotypes with associated differences in clinical phenotypes.
Background
Antigen‐specific IgE binds the Fcε receptor I (FcεRI) expressed on several types of immune cells, including dendritic cells (DCs). Activation of FcεRI on DCs in atopics has been shown to modulate immune responses that potentially contribute to asthma development. However, the extent to which DC subsets differ in FcεRI expression between atopic children with or without asthma is currently not clear. This study aimed to analyse the expression of FcεRI on peripheral blood mononuclear cells (PBMCs) from atopic children with and without asthma, and non‐atopic/non‐asthmatic age‐matched healthy controls.
Methods
We performed multiparameter flow cytometry on PBMC from 391 children across three community cohorts and one clinical cohort based in Western Australia.
Results
We confirmed expression of FcεRI on basophils, monocytes, plasmacytoid and conventional DCs, with higher proportions of all cell populations expressing FcεRI in atopic compared to non‐atopic children. Further, we observed that levels of FcεRI expression were elevated across plasmacytoid and conventional DC as well as basophils in atopic asthmatic compared to atopic non‐asthmatic children also after adjusting for serum IgE levels.
Conclusion
Our data suggest that the expression pattern of FcεRI on DC and basophils differentiates asthmatic from non‐asthmatic atopic children. Given the significant immune modulatory effects observed as a consequence of FcεRI expression, this altered expression pattern is likely to contribute to asthma pathology in children.
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