Abstract 389: The Role of Amadori-Glycation in High Density Lipoprotein Dysfunction and Oxidative Stress in Patients With Diabetes

Abstract

Objectives: Diabetes is associated with HDL dysfunction and oxidative stress. We recently demonstrated that HDL from patients with T2D has reduced anti-oxidant activity and it is pro-inflammatory. Here we used the 2 H 2 O-based metabolic labeling approach to test the hypothesis that hyperglycemia-induced glycation contributes to HDL dysfunction and oxidative stress in diet-controlled patients with T2D. Methods: HDL from patients with T2D and age- and BMI-matched healthy controls (n=7/group) was isolated and it’s anti-oxidant and cholesterol efflux properties were quantified. ApoAI cross-linking and HDL particle size distribution were anlyzed. HDL proteome composition and post-translational modification of proteins were quantified by shot-gun proteomics aproach. Metabolic 2 H 2 O-labeling coupled with high resolution mass spectrometry was applied to quantify HDL turnover and HDL proteome dynamics. Results: Despite significant differences in fasting blood glucose, insulin, insulin resistance and HbA1c, patients with T2D and controls had similar lipid (triglycerides, total cholesterol, and HDL cholesterol) and lipoprotein (apoAI and apoB100) profile. HDL from patients with T2D displayed increased levels of cross-linked apoAI and lipid-poor pre-β1 HDL partcicles. ApoB-depleted serum from T2D patients had reduced PON1 activity and macrophage-cholesterol efflux capacity, and increased levels of lipid peroxidation products measured as TBARS (all P<0.05 ). HDL from patients with T2D was enriched with Amadori glycated apoAI and transferrin (Tf), the key HDL proteins involved in cholesterol and iron transport. The extent of glycations were associated with increased degradation of apoAI and Tf. ApoAI glycation was inversely correlated with ABCA1-induced cholesterol efflux activity of HDL (r=-0.52, P<0.005), while Tf glycation had positive association with the TBARS levels (r=0.40, P<0.05). Our in vivo HDL flux study demonstrated that glycated apoAI and Tf species were degraded 3 and 10 fold faster than the respective non-modified native proteins. Conclusions: HDL dysfunction and oxidative stress in T2D is related to glycation-induced instability of HDL proteins, including apoAI and Tf.