Plasma advanced glycation end-products and skin autofluorescence are increased in COPD

Chronic obstructive pulmonary disease (COPD) is associated with systemic inflammation and oxidative stress. These conditions may lead to the formation of advanced glycation end-products (AGEs). In this study we investigated in 88 COPD patients and 55 control subjects (80% ex-smokers) the association of the plasma protein-bound AGEs N(ε)-(carboxymethyl)lysine (CML), pentosidine, N(ε)-(carboxyethyl)lysine (CEL), and AGE accumulation in skin by skin autofluorescence (AFR), with lung function. Mean ± sd plasma CML was decreased (COPD 61.6 ± 15.6 nmol · mmol(-1) lysine, never-smokers 80.7 ± 19.8 nmol · mmol(-1) lysine and ex-smokers 82.9 ± 19.3 nmol · mmol(-1) lysine) and CEL (COPD 39.1 ± 10.9 nmol · mmol(-1) lysine, never-smokers 30.4 ± 5.0 nmol · mmol(-1) lysine and ex-smokers 27.7 ± 6.4 nmol · mmol(-1) lysine) and AFR (COPD 3.33 ± 0.67 arbitrary units (AU), never-smokers 2.24 ± 0.45 AU and ex-smokers 2.31 ± 0.47 AU) were increased in COPD patients compared to controls. Disease state was inversely associated with CML, and linearly associated with CEL and AFR. Performing regression analyses in the total group, CEL and AFR showed a negative association and CML a positive association with lung function, even after correction for potential confounders. In conclusion, CEL and AFR were negatively and CML was positively associated with disease state. In the total group only the AGEs showed an association with forced expiratory volume in 1 s. Our data suggest that AGEs are involved in the pathophysiology of COPD, although their exact role remains to be determined.