The atopic march: IgE is not the only road

Abstract

Eczema, allergic rhinitis, and asthma are common diseases of childhood around the world, especially in high-income countries. 1 Deckers IA McLean S Linssen S Mommers M van Schayck CP Sheikh A Investigating international time trends in the incidence and prevalence of atopic eczema 1990–2010: a systematic review of epidemiological studies. PLoS One. 2012; 7: e39803 Crossref PubMed Scopus (332) Google Scholar , 2 Sly RM Changing prevalence of allergic rhinitis and asthma. Ann Allergy Asthma Immunol. 1999; 82: 233-248 Summary Full Text PDF PubMed Google Scholar These diseases usually occur in the same individual, which could be a result of a pathophysiological link. 3 Dharmage SC Lowe AJ Matheson MC Burgess JA Allen KJ Abramson MJ Atopic dermatitis and the atopic march revisited. Allergy. 2013; (published online Oct 14.)https://doi.org/10.1111/all.12268 Crossref Scopus (240) Google Scholar The interaction between these comorbidities is typically known as the atopic march, in which eczema or atopic dermatitis progresses to allergic rhinitis and asthma. 4 Zheng T Yu J Oh MH Zhu Z The atopic march: progression from atopic dermatitis to allergic rhinitis and asthma. Allergy Asthma Immunol Res. 2011; 3: 67-73 Crossref PubMed Scopus (277) Google Scholar Indeed, several cohort studies have shown that a diagnosis of eczema significantly increases the risk of developing either allergic rhinitis or asthma. This risk is greater among children who produce IgE antibodies in response to environmental triggers than in children who do not, which suggests that allergic sensitisation is an important factor. 3 Dharmage SC Lowe AJ Matheson MC Burgess JA Allen KJ Abramson MJ Atopic dermatitis and the atopic march revisited. Allergy. 2013; (published online Oct 14.)https://doi.org/10.1111/all.12268 Crossref Scopus (240) Google Scholar However, the risk of developing asthma among children with eczema is partly confounded by viral infections and this atopic march can also occur in the absence of underlying allergic sensitisation. 3 Dharmage SC Lowe AJ Matheson MC Burgess JA Allen KJ Abramson MJ Atopic dermatitis and the atopic march revisited. Allergy. 2013; (published online Oct 14.)https://doi.org/10.1111/all.12268 Crossref Scopus (240) Google Scholar , 5 Khan SH Park SS Sirajuddin IA Grayson MH Respiratory virus and asthma: the role of immunoglobulin E. Clin Ther. 2008; 30: 1017-1024 Summary Full Text PDF PubMed Scopus (11) Google Scholar Therefore, the atopic march is not just a simple temporal relationship explained by increased concentrations of IgE, but instead it is a complex process affected by different environmental and genetic factors. Understanding what proportion of these allergic comorbidities occur as a result of allergic sensitisation is important for prevention and to provide a better understanding of the pathophysiology of allergic comorbidities. Comorbidity of eczema, rhinitis, and asthma in IgE-sensitised and non-IgE-sensitised children in MeDALL: a population-based cohort studyCoexistence of eczema, rhinitis, and asthma in the same child is more common than expected by chance alone—both in the presence and absence of IgE sensitisation—suggesting that these diseases share causal mechanisms. Although IgE sensitisation is independently associated with excess comorbidity of eczema, rhinitis, and asthma, its presence accounted only for 38% of comorbidity, suggesting that IgE sensitisation can no longer be considered the dominant causal mechanism of comorbidity for these diseases. Full-Text PDF