Responses of Airway Epithelium to Environmental Injury: Role in the Induction Phase of Childhood Asthma

Figure 1

Environmental irritants may activate various pattern recognition receptors on AEC or may be directly toxic to the cells. Exposure to such irritants frequently causes oxidant injury to AEC, leading to generation of reactive oxygen species and upregulation of antioxidant enzyme systems. In parallel, intracellular signalling pathways are activated, triggering production of cytokines that can recruit and stimulate DC, upregulate their expression of costimulatory molecules and promote Th2 polarisation of the CD4+ T-cell response. These cytokines may also activate various populations of innate helper cells, leading to expansion of the Th2 cell population and helping to drive the allergic inflammatory response.