The multiple trajectories of the allergic march

Abstract

The allergic march has long responded to a scenario of the sequential appearance of different allergic comorbidities. However, the variability in the appearance and progression of different allergic diseases draws a heterogeneous scenario that does not respond to a linear and unique trajectory. Although currently almost half of the child population presents at least one allergy symptom, only 4-6% present multimorbidity, with several allergic entities coexisting. It has recently been shown that although they share etiological mechanisms and risk factors, these allergic diseases arise independently. In most cases a consecutive progression is not observed, or at least not the same in all patients. Inflammation mediated by T helper 2 (Th2) cells, epithelial barrier dysfunction and genetic predisposition plays a fundamental role in the etiology of these diseases, on which the interaction with the exposome acts decisively. Therefore, the study of diseases from an omics point of view is essential to describe the different trajectories of allergic progression and propose effective interventions to avoid multimorbidity scenarios. In this narrative review, we provide an overview of the current perception of allergic march, including clinical observations, omics data, risk factors, and preventative measures proposed for modifying its course or even preventing its onset.