Fig. 1.

Main components of inflammatory signalling in asthma triggered by exposure to environmental pollutants. The pollutants come into contact with the airway epithelium and trigger the generation of reactive oxygen species (ROS). Moderate or high levels of ROS may activate Th2 or Th17 inflammatory response mechanisms triggered by the release of different cytokines and proinflammatory factors and the involvement of different immune cell lineages (neutrophils, eosinophils). DEP: diesel exhaust particles; IL: interleukin; ILC-2: type 2 innate lymphoid cells; NLR: NOD-like receptor; ROS: reactive oxygen species; TLR: toll-like receptor; TSLP: thymic stromal lymphopoietin.