Levels of Soluble Receptor for Advanced Glycation End Products in Bronchoalveolar Lavage Fluid in Patients with Various Inflammatory Lung Diseases

Receptor for advanced glycation end products (RAGE) is a multiligand receptor of S100/calgranulins, high-mobility group box 1, and others, and it is associated with the pathogenesis of various inflammatory and circulatory diseases. The soluble form of RAGE (sRAGE) is a decoy receptor and competitively inhibits membrane-bound RAGE activation. In this study, we measured sRAGE levels in bronchoalveolar lavage fluid (BALF) of 78 patients, including 41 with interstitial pneumonia, 11 with sarcoidosis, 9 with respiratory infection, 7 with ARDS, 5 with lung cancer, and 5 with vasculitis. Among them, sRAGE was detectable in BALF of 73 patients (94%). In patients with ARDS and vasculitis, the sRAGE levels were significantly higher than in the control subjects and those with interstitial pneumonia. The sRAGE levels were positively correlated with total cell counts in BALF and serum levels of surfactant protein-D, lactate dehydrogenase, and C-reactive protein. There was an inverse correlation between PaO₂/FIO₂ ratio and sRAGE levels. These results indicate that sRAGE in BALF might be considered as a biomarker of lung inflammatory disorders, especially ARDS and vasculitis.