The Atopic March and Atopic Multimorbidity: Many Trajectories, Many Pathways

Publication date: Available online 17 November 2018

Source: Journal of Allergy and Clinical Immunology

Author(s): Amy S. Paller, Jonathan M. Spergel, Paola Mina-Osorio, Alan D. Irvine

Abstract

The "atopic march" recognizes the increased occurrence of asthma and/or allergic rhinitis after atopic dermatitis (AD) onset. Mechanisms for developing atopic comorbidities after AD onset are poorly understood, but may involve the impaired cutaneous barrier, which facilitates cutaneous sensitization. The association may also be driven or amplified in susceptible individuals by a systemic Th2-dominant immune response to cutaneous inflammation. However, these associations may merely involve shared genetic loci and environmental triggers, including microbiome dysregulation, with the temporal sequence reflecting tissue-specific peak time of occurrence of each disease, suggesting more of a clustering of disorders than a march. Prospective longitudinal cohort studies provide an opportunity to explore the relationships between post-dermatitis development of atopic disorders and potential predictive phenotypic, genotypic, and environmental factors. Recent investigations implicate disease severity and persistence, age of onset, parental atopic history, FLG (filaggrin) mutations, polysensitization, and the non-rural environment among risk factors for development of multiple atopic comorbidities in young children with AD. Early intervention studies to repair the epidermal barrier or alter exposure to the microbiome or allergens may elucidate the relative roles of barrier defects, genetic locus alterations, and environmental exposures in the risk and sequence of occurrence of Th2 activation disorders.

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