Study of the Association between Thiols and Oxidative Stress Markers in Children with Obesity

Abstract

Obesity has reached epidemic proportions, and the World Health Organization defined childhood overweight and obesity as a noncommunicable disease that represents the most serious public health challenges of the twenty-first century. Oxidative stress, defined as an imbalance between oxidants and antioxidants causing an impairment of the redox signals, is linked to the development of metabolic diseases. In addition, reactive oxygen species generated during metabolic disorder could increase inflammation, causing the development of insulin resistance, diabetes, and cardiovascular disease. We analyze serum levels of cysteine (Cys), cysteinyl-glycine (Cys-Gly), homocysteine (Hcy), and glutathione (GSH), and other markers of oxidative stress, such as thiobarbituric acid reactive substances (T-BARS), 8-isoprostane, and protein carbonyl in our children with obesity. Total antioxidant status was also determined. We found lower GSH and Cys-Gly levels, and higher Hcy and oxidative stress markers levels. We also found a positive correlation between Body Mass Index (BMI), Cys, GSH, and Hcy levels, between insulin and Cys levels, and between BMI and the homeostasis model assessment-estimated insulin resistance (HOMA-IR) with 8-isoprostane levels. Finally, we found a correlation between age and GSH and Cys levels. The deficiency of GSH could be restored by dietary supplementation with GSH precursors, supplying an inexpensive approach to oppose oxidative stress, thus avoiding obesity complications.

Keywords: glutathione; obesity; oxidative stress; thiols.

Figure 1

Comparisons of cholesterol and thiol levels. (A) Concentrations of Total, LDL and HDL cholesterol, expressed as mg/dL. (B) Cysteine (Cys) and cysteinyl-glycine (Cys-Gly) levels. (C) Concentrations of homocysteine (Hcy), and glutathione (GSH). Thiol levels are expressed as μmol/L. * p < 0.05; ** p < 0.01. All parameters are presented as mean ± standard deviation. Abbreviations: controls (CTRL); high-density lipoproteins (HDL); low-density lipoproteins (LDL).

Figure 2

Oxidative stress parameter and antioxidant levels. (A) T-BARS levels, expressed as malondialdehyde (MDA) equivalent; (B) 8-isoprostane levels; (C) concentrations of protein carbonyl. Total antioxidants levels, expressed as Trolox equivalents, are reported in (D). * p < 0.05; ** p < 0.01. All parameters are presented as mean ± standard deviation.

Figure 3

Correlations between thiol levels, oxidative stress parameters, antioxidant levels, and the other parameters studied. Values are expressed as Spearman correlation coefficient (r) (A). Color explanation is reported in (B), with the scale ranging from negative correlation (red) to positive correlation (blue). White box indicates no correlation.