Decreased circulatory receptor for advanced glycation end-products is associated with poorer survival in patients with idiopathic pulmonary fibrosis

Background: The receptor for advanced glycation end-products (RAGE) is highly expressed in alveolar type 1 pneumocytes and expression of RAGE is decreased in lung of idiopathic pulmonary fibrosis (IPF). However, there has been no study investigating circulatory RAGE levels in patients with IPF. Aim: We conducted this study to determine circulatory RAGE levels and the association between RAGE levels and survival in patients with IPF. Methods: Thirty-eight IPF patients and 81 control subjects were enrolled in this study. Serum concentrations of soluble RAGE (sRAGE) were measured using an enzyme-linked immunosorbent assay. Overall survival rates in IPF patients were analyzed by the Kaplan-Meier method applying cutoff values determined by the ROC curve analysis. Results: The median follow-up period for the patients with IPF was 20.6 months. Serum levels of sRAGE was significantly decreased in patients with IPF (569.0 ± 41.6 pg/ml) compared with control subjects (826.1 ± 37.6 pg/ml) (p l 0.001). The patients with IPF were categorized by their serum sRAGE levels (as above or below the cut-off level of 625 pg/mL) and their survival estimated using the Kaplan–Meier method. The difference in median survival between the two groups was significant (p l 0.05). The IPF patients with low levels of sRAGE (l 625 pg/mL) had shorter survival (2-year survival rate: 56%) compared with those with high levels of sRAGE (2-year survival rate: 100%). Conclusions: Circulatory sRAGE levels are decreased in patients with IPF compared with control subjects. Decreased sRAGE is associated with poorer survival in patients with IPF.