1333-P: Increased Spare Respiratory Capacity in Circulating Cells and Decreased Serum Antioxidant Defense Mechanisms in Obese Children

Abstract

With increasing rates of childhood obesity, diagnoses of insulin resistance and type 2 diabetes (DM) in children is on the rise. Mitochondrial dysfunction is associated with insulin resistance and DM, therefore bioenergetics profiling of circulating cells may serve as a marker for mitochondrial dysfunction in insulin resistant subjects. The advantage of this biomarker is that others currently in use may not exhibit alterations until symptoms are already present. Mitochondrial bioenergetics (Seahorse XF96) was measured in peripheral blood mononuclear cells (PBMCs) and platelets. Levels of oxidative stress, post-translational modifications of protein tyrosine residues, 3-Nitrotyrosine and 3-Chlorotyrosine, reduced (GSH) and oxidized (GSSG) glutathione, as well as whole-body D31-palmitate oxidation were also assessed in healthy lean (HL; n=18), and overweight/obese (OW/OB; n=29) (BMI ≥85th percentile) 5-9 years old children. While maximal respiration was not different, the reserve capacity (RC) was increased in OW/OB compared to HL subjects in PBMC (45,6±4,7 vs. 32,1±7.7; p=0.05) and platelet (65,3±3.7 vs. 31,2±6,7; p=0.001). Importantly, 20% of these children already presented HbA1c levels above 6.5%. Moreover, 3-Chlorotyrosine was elevated (52,0±3,1 vs. 40,7±1,8; p=0.05), while GSH/GSSG and cysteine/cysteine (intracellular, extracellular redox buffers, respectively) tended to be decreased. Palmitate oxidation is being quantified. RC is a critical component of the cell’s bioenergetics and can be used during increases in energy demand. Our results suggest significant metabolic adjustments to an excess in substrate availability and already compromised antioxidant defenses in 5-9 year old OW/OB children. Oxidative stress and damage occur when antioxidant defense mechanisms fail to counter-balance and control reactive oxygen species generated from endogenous oxidative metabolism or from pro-oxidant environmental exposures. Disclosure E. Carvalho: None. S. Rose: None. M. Cotter: None. S.C. Bennuri: None. L.M. Delhey: None. G.A. Goode: None. A. Beebe: None. E. Børsheim: None. Funding National Institute of General Medical Sciences (P20GM109096)