The receptor for advanced glycation end-products (RAGE) and its soluble forms are predominantly expressed in lung but its physiological importance in this organ is not yet fully understood. Since RAGE acts as a cell adhesion molecule, we postulated its physiological importance in the respiratory mechanics. Respiratory function in a buffer-perfused isolated lung system and biochemical parameters of the lung were studied in young, adult, and old RAGE knockout (RAGE-KO) mice and wild-type (WT) mice. Lungs from RAGE-KO mice showed a significant increase in the dynamic lung compliance and a decrease in the maximal expiratory air flow independent of age-related changes. We also determined lower mRNA and protein levels of elastin in lung tissue of RAGE-KO mice. RAGE deficiency did not influence the collagen protein level, lung capillary permeability, and inflammatory parameters (TNF-␣, high-mobility group box protein 1) in lung. Overexpressing RAGE as well as soluble RAGE in lung fibroblasts or cocultured lung epithelial cells increased the mRNA expression of elastin. Moreover, immunoprecipitation studies indicated a trans interaction of RAGE in lung epithelial cells. Our findings suggest the physiological importance of RAGE and its soluble forms in supporting the respiratory mechanics in which RAGE trans interactions and the influence on elastin expression might play an important role.receptor for advanced glycation end-products; aging; biomechanics; elastin; mouse THE RECEPTOR FOR ADVANCED glycation end-products (RAGE) is a pattern recognition receptor of the immunoglobulin superfamily (32). RAGE is predominantly expressed in lung, particularly in the type I alveolar epithelial (ATI) cells (12,15,46). This specific localization suggests its important physiological function in the alveolar epithelium. In other cell types and tissues, the expression of RAGE is activated in response to pathophysiological conditions, such as the accumulation of advanced glycation end-products (AGEs) and inflammation (1). RAGE expression is highly associated with lung development and increases during the alveolarization (29,40). High RAGE expression prior to the alveolarization period has adverse effects associated with a severe pulmonary dysplasia (16,41). A reduced alveolar expression of RAGE is related to pathophysiological changes of the lung tissue, such as carcinoma (3), fibrosis (34, 37), and chronic obstructive pulmonary disease (COPD) (34). In addition to the membrane-bound receptor, soluble RAGE (sRAGE) forms exist as the result of either alternative splicing (22) or protein shedding by metalloproteinases (39, 52). sRAGE normally exists in the bronchoalveolar lavage (BAL) at a high level (53), but it is deficient in neutrophilic asthma and COPD (47, 49).The physiological importance of RAGE in lung is not yet fully understood because mice lacking RAGE do not show obvious pulmonary alterations (5, 9). Only intervention studies indicated an adverse effect of RAGE in the development of lung fibrosis (14, 19) and acute lung injury (4...