Chapter 5: Manganese Transport Across the Pulmonary Epithelium

Our lungs represent a significant exposure site to airborne metals. Manganese and other metals enter the bloodstream from a variety of airborne sources across the pulmonary epithelium. Once absorbed, manganese can be taken up by other organ systems like the brain, where it is known to exert neurotoxic effects. Models of pulmonary manganese absorption have been developed based on known pathways of uptake across the intestinal epithelium, which are regulated by iron status. The sum of evidence suggests that additional and perhaps unique transport pathways are available to manganese in order to transit the pulmonary epithelium. Both in vitro and in vivo models have been established to characterize not only the transport but also toxicity of manganese on pulmonary epithelial cells. Handling of manganese by the lungs plays an important role in the inflammatory response, and has a strong influence on lung infection. These issues and emerging new questions are discussed in this chapter.