RESUMEN
The role of the receptor for advanced glycation end products (RAGE) in promoting the inflammatory response through activation of NF-κB pathway is well established. Recent findings indicate that RAGE may also have a regulative function in apoptosis, as well as in cellular proliferation, differentiation, and adhesion. Unlike other organs, lung tissue in adulthood and during organ development shows relatively high levels of RAGE expression. Thus a role for the receptor in lung organogenesis and homeostasis may be proposed. To evaluate the role of RAGE in lung development and adult lung homeostasis, we generated hemizygous and homozygous transgenic mice overexpressing human RAGE, and analyzed their lungs from the fourth postnatal day to adulthood. Moderate RAGE hyperexpression during lung development influenced secondary septation, resulting in an impairment of alveolar morphogenesis and leading to significant changes in morphometric parameters such as airspace number and the size of alveolar ducts. An increase in alveolar cell apoptosis and a decrease in cell proliferation were demonstrated by the terminal deoxy-nucleotidyltransferase-mediated dUTP nick end labeling reaction, active caspase-3, and Ki-67 immunohistochemistry. Alterations in elastin organization and deposition and in TGF-ß expression were observed. In homozygous mice, the hyperexpression of RAGE resulted in histological changes resembling those changes characterizing human bronchopulmonary dysplasia (BPD). RAGE hyperexpression in the adult lung is associated with an increase of the alveolar destructive index and persistent inflammatory status leading to "destructive" emphysema. These results suggest an important role for RAGE in both alveolar development and lung homeostasis, and open new doors to working hypotheses on the pathogenesis of BPD and chronic obstructive pulmonary disease.