Objective: In obesity, the combined effects of enhanced food consumption, enhanced oxidative stress and microinflammation could augment the advanced glycation end products (AGEs) accumulation in plasma. We compared the plasma concentrations of AGEs and the soluble receptor for AGEs (sRAGE) in relation to markers of oxidative stress, microinflammation and renal function in obese and lean children/adolescents.
Methods: In 18 apparently healthy obese children/adolescents (7 females/11 males; age: 5-18 years; body mass index, BMI: 27.3+/-3.3 kg/m2) and 18 healthy lean controls (10 females/8 males; age: 4-17 years, BMI: 22.4+/-2.1 kg/m2) the plasma concentration of N(epsilon)-carboxymethyllysine (CML), fructoselysine (FL), AGE-associated fluorescence, sRAGE, high sensitive-C-reactive protein (hsCRP), interleukin-6 (IL-6) and urinary 8-hydroxy-2-deoxyguanosine (U-8-OHdG) excretion, plasma advanced oxidation protein products (AOPPs), renal function, and the HOMA index of insulin resistance were determined.
Results: Obese children/adolescents had significantly lower concentrations of plasma FL (6.8+/-0.3 mmol/mol lysine vs. 7.7+/-0.3, p<0.02), CML (0.14+/-0.03 mmol/mol lysine vs. 0.22+/-0.04, p<0.001), and fluorescent AGEs (223+/-37 arbitrary units (AU) vs. 318+/-64, p<0.01) than their lean counterparts. Plasma sRAGE concentration did not differ (2.3+/-0.6 ng/ml vs. 2.6+/-0.6). Obese children/adolescents were more insulin-resistant (HOMA index: p<0.01), exhibited higher levels of markers of inflammation (hs-CRP: p<0.03; IL-6: p<0.02), of oxidative stress (AOPPs: p<0.05; 8-OHdG: p<0.04) and had a higher creatinine clearance (p<0.01) and proteinuria (p<0.01).
Conclusions: We present the first evidence that childhood/adolescent obesity is characterized by lower plasma AGE levels, despite lower insulin sensitivity, enhanced oxidative stress and microinflammation. An enhanced removal of AGE peptides via hyperfiltration may partially contribute to the lower plasma AGE levels.