The AGE reader: a non-invasive method to assess long term tissue damage

Abstract Aims Advanced glycation endproducts (AGEs) are sugar modified adducts which arise during non-enzymatic glycoxidative stress. These compounds may become systemically elevated in disease states, and accumulate in tissue, especially on long-lived proteins. AGEs have been implicated in various acute, and chronic diseases, stressing the need for reliable and comprehensive measuring techniques. Measurement of AGEs in tissue such as skin requires skin biopsies, which is an invasive procedure. The AGE Reader has been developed to assess skin autofluorescence (SAF) non-invasively by the fluorescent properties of several AGEs. Results/Conclusion Various studies have shown that SAF is a useful marker of disease processes associated with oxidative stress. It is prospectively associated with development of cardiovascular events in patients with diabetes, renal or cardiovascular disease, and it predicts diabetes, cardiovascular disease and mortality in the general population. However, when measuring SAF in individual subjects, several factors may limit the reliability of the measurement, and hamper its use as a systemic biomarker for AGEs. These include endogenous factors present in the skin that absorb emission light such as melanin in dark-skinned subjects, but also factors that lead to temporal changes in SAF such as acute diseases and strenuous physical exercise associated with glycoxidative stress. Also, exogenous factors could potentially influence SAF levels inadvertently such as nutrition, and for example the application of skin care products. This review will give an overview of the AGE Reader functionality and the intrinsic, and exogenous factors which potentially influence the SAF assessment in individual subjects.