Innate immune response and bronchiolitis and preschool recurrent wheeze

Abstract

Bronchiolitis and preschool recurrent wheeze (PSRW) are common paediatric problems causing significant morbidity and mortality in the first years of life. Respiratory syncytial virus (RSV) and rhinoviruses are the commonest pathogens associated with these illnesses. Why some infants are severely affected, requiring admission to hospital, whilst others experience a simple cold is not fully understood: research has suggested that the innate immune response to these viruses is important. The innate immune system has many components and activation or deficiency in one or many areas may explain the different clinical presentations and disease severities that can occur in these infants. This review will summarize the recent evidence highlighting how RSV and rhinoviruses may modulate the innate immune response in both bronchiolitis and PSRW, and discuss how these illnesses affect the long-term development of the infant lung and the possible susceptibility to persistent airway disease.

Figure 1

The wheezing phenotypes. (a) Tucson classification of four wheezing phenotypes. TEW: transient early wheezers; LOW, late-onset wheezers; PW, persistent wheezers; NW, never wheezed. (b) Avon Longitudinal Study of Parents and Children (ALSPAC) classification of six wheezing phenotypes. ETW, early-onset transient wheezers; ITW, intermediate-onset transient wheezers; EPW, early-onset persistent wheezers; IPW, intermediate-onset persistent wheezers; LW, late-onset wheezers; NW, never wheezed.

Figure 2

Interactions between respiratory viruses, environmental factors, bronchiolitis, preschool recurent wheeze, the innate immune system and the subsequent development of airways disease. LRTI, lower respiratory tract infection; URTI, upper respiratory tract infection.