Respiratory Viruses, Eosinophil Activation, and Early Allergen Sensitization - Early Life Predictors of Persistent Wheezing and Asthma

Abstract

Approximately 20% of all children will suffer from wheezing illnesses, and in 1-3% of all infants, respiratory distress is severe enough to require hospitalization. As wheezing infants form a heterogeneous group with different phenotypes and outcomes, it is still a challenge to identify those who will go on wheezing to develop asthma. In order to facilitate the prediction of later asthma, algorithms have been developed for clinical use. The algorithms validated this far are based on personal atopic findings and the parental history of asthma, and blood eosinophilia has been the only laboratory marker included. In this review, we will focus on the role of respiratory viruses, eosinophil activation markers, specific immunoglobulin E antibodies, and skin prick tests, as early life predictors of persistent wheezing and asthma.According to recently published results, rhinoviral infection seems to carry a high risk for persistence of wheezing. Sensitization to inhalant allergens in infancy strongly increases the risk for later respiratory allergy. Eosinophil activation markers seem not to offer significant additional value over blood eosinophils.Determination of viral etiology of wheeze, and/or screening for early sensitization to inhalant allergens in individuals with no clinically evident atopy might be of use in identifying future asthmatics.

Wheezing due to rhinovirus infection in infancy: Bronchial hyperresponsiveness at school age

“…Early exposure to furry animals leading to sensitization was found to be associated with increased bronchial responsiveness at school age. That is consistent with current literature stressing the role of sensitization to inhalant allergens as a predictor of persistent wheezing 27,28 . In addition, rhinovirus infection‐induced wheezing in infancy was associated with increased bronchial responsiveness at school age.…”

“…The authors did not specify the viral etiology of wheeze in RSV‐negative children, and the role of rhinoviruses, for instance, remained open. Rhinoviruses, however, are commonly encountered in wheezing children in early childhood, 28 and often precipitate asthma symptoms in school children 30 . In addition, studies on experimental rhinovirus infections in adults have reported increased airway responsiveness in allergic subjects compared with non‐allergic ones, 31 and significantly reduced FEV 1 in home recordings by patients with mild atopic asthma 32 .…”