Possible role of amino acids, peptides, and sugar transporter in protein removal and innate lung defense.

This review presents the hypothesis that removal of polypeptides and glycoproteins from the alveolar space and airways is mediated in part by enzymatic degradation, followed by transporter mediated transepithelial transport of amino acids, peptides and sugar residues. Furthermore, the activity of these transporters ensures low availability of nutrients, and decrease bacterial growth. Thus, airway epithelial transporters for sugar, amino acids, peptides and other nutrients can contribute to the innate lung defense.