Figure 2.

Proposed iron regulation in lung. The level of iron in alveolar epithelial cells is mainly regulated by TfR1, DMT1, ZIP8, LfR, and FPN receptors. Alveolar macrophages, through phagocytosis of bacteria, play an important role in lung defense response. Fpn, ferroportin; ZIP8, zinc transporter SLC39A8; Lfn, lactoferrin; LfR, lactoferrin receptor; DMT1, divalent metal transporter 1; TfR1, transferrin receptor 1; NRAMP1, natural resistance–associated macrophage protein 1NGAL, neutrophil gelatinase–associated lipocalin (modified according to Zhang et al., 2019 [35]).