Supplementary methods. Sputum induction, bronchial biopsies, skin auto-fluorescence. Supplementary Table 1. AGE and RAGE expression in young and old never-smokers and smokers, and COPD GOLD stages. Supplementary Table 2. Correlations of AGEs and RAGE between different compartments. Supplementary Table 3. Expression QTL analysis of AGER. Supplementary Table 4. SNP association with AGE levels detected in the skin. Supplementary Figure 1. Quantitative analyses of AGEs (left panel) and RAGE (right panel) expression in A) intact epithelium, B) basal epithelium, C) smooth muscle, D) connective tissue of bronchial biopsies. Intensity of staining was scored by a 4-points scale: 0=negative staining, 1=weak positive, 2=positive, and 3=strong positive. Horizontal bars represent median values. Supplementary Figure 2. Representative immunohistological staining of AGEs (AGE 1/750, Cosmo Bio Clone 6D12) and RAGE (RAGE 1/1500, Abcam, ab7764) in young healthy controls, old healthy controls and COPD patients. Pictures are shown as 40x magnification, scans taken using the Hamamatsu Slide Scanner (Hamamatsu Photonics, Hamamatsu City, Japan). Supplementary Figure 3. Quantitative analyses of AGEs (left panel) and RAGE (right panel) expression in A) epithelium and B) smooth muscle of the peripheral airways. Intensity of staining was scored by a 4-points scale: 0=negative staining, 1=weak positive, 2=positive, and 3=strong positive. Horizontal bars represent median values.