Contribution of Lung Macrophages to the Inflammatory Responses Induced by Exposure to Air Pollutants

Figure 3

The impact of PM exposure on alveolar macrophage phenotype. PM exposure stimulates macrophages (predominantly M1 phenotype) to produce proinflammatory mediators that attract other immune cells such as neutrophils into the airspaces. Following phagocytosis of the PM, these cells undergo apoptosis and are removed by M2 macrophages, which also produce anti-inflammatory mediators that are pivotal for resolution of the inflammatory response induced by the PM exposure. Persistent inflammation in the lung induced by PM exposure may be due to PM that blocks macrophage switching (M1 to M2), compromising efferocytosis.