Nuclear damage in peripheral lymphocytes of obese and overweight Italian children as evaluated by the γ‐H2AX focus assay and micronucleus test

Abstract

Childhood obesity, often characterized by a chronic low-grade inflammation, has been associated with an increased risk of developing some types of cancer later in life. Nuclear γ-H2AX foci represent the first detectable response of cells to DNA tumorigenesis lesions, such as the double-strand breaks (DSBs). An excess of micronucleated peripheral lymphocytes was found in subjects with cancer or inflammation-based diseases. We set out to investigate the expression of genome damage, from DNA lesions to chromosome mutations (micronuclei), in overweight and obese children. Using the γ-H2AX focus assay and micronucleus (MN) test, we analyzed peripheral lymphocytes from 119 Italian children classified as normal weight (n=38), overweight (n=20), or obese (n=61). Cultures treated with bleomycin (BLM) were also set up for each child in both assays to check functioning of the apparatus that ensures DNA integrity. We measured serum TNF-α, IL-6, and C-reactive protein (CRP) as markers of inflammation. Overweight and obese children had significantly higher levels of H2AX phosphorylation (0.0191±0.0039 and 0.0274±0.0029 γ-H2AXF/n) and increased MN frequencies (2.30±0.25 and 2.45±0.22‰) than normal-weight children (0.0034±0.0006 γ-H2AXF/n, and 0.92±0.12‰ MN), while all subjects responded to BLM induction, irrespective of their weight status. The fold increase of spontaneous MN frequencies in overweight and obese subjects was 2.5 and 2.7, respectively, well below the corresponding increase in the γ-H2AX foci (5.6- and 8.0-fold, respectively). IL-6 and CRP mean values were significantly higher in obese and overweight children than in controls. Here, we demonstrated that peripheral cells of overweight and obese children showed increased levels of DSBs, which were not completely repaired as part of them has been converted into micronuclei. Characterization of childhood obesity inflammation could be implemented using molecular markers of genome damage.

Air pollution biological effects in children living in Lecce (Italy) by Buccal micronucleus cytome assay (the MAPEC_LIFE study)

“…This positive correlation is confirmed by the literature for both peripheral lymphocytes [34] and BM cells [35] in school-age children.…”

“…Of these, 270 (78.7%) were valid, after excluding those that were either incomplete (59) or did not meet the criteria for inclusion (34). Overall, in the first season, 266 children were sampled (98.5%) (four children were absent at the moment of sampling).…”

Mutagenic potential of Cordia ecalyculata alone and in association with Spirulina maxima for their evaluation as candidate anti-obesity drugs

“…Therefore, the search for new treatments that could assist in weight reduction while not conferring additional health risks is necessary (Scarpato et al, 2011;Boeing, 2013;Lehnert et al, 2013;Gilbert and Slingerland, 2013).…”

Transcriptional Alterations of ET-1 Axis and DNA Damage in Lung Tissue of a Rat Obesity Model

“…Consistent with our findings, activation of the DDR response has been reported in a multistep inflammation-based lung cancer rat model, with higher levels of g-H2AX being observed in precancerous tissues than in tumors (Blanco et al, 2007). Even more relevant is a recent study in which, compared to normal weight controls, an eight-fold increase in g-H2AX nuclear foci was observed in peripheral lymphocytes of overweight/obese children and adolescents; after repair of the initial amount of DNA lesions took place, the prevalence of genetically unstable cells harboring micronuclei was reduced to only two-fold (Scarpato et al, 2011). This confirms that the obesity condition is sustained by a chronic systemic inflammation, as the generation of endogenous molecules that are able to damage the DNA of the cells is not limited to the adipose tissue alone but can also occur and/or diffuse to other organs (i.e., the lung).…”

“…However, cells respond promptly by activating the DNA damage response (DDR), which precociously results in phosphorylation of Ser-139 of histone H2AX at the site of DNA damage (g-H2AX foci) (Rogakou et al, 1998). Thus, identification of g-H2AX in the nuclei of a given cell population is considered an excellent marker of early DNA damage, and several authors used the g-H2AX assay, this including either the focus version (immunofluorescence analysis of cell lines) or the positive nucleus version (immunohistochemistry analysis of paraffin-embedded tissue cells) to study the response of physical or chemical genotoxins and to correlate DSB formation with exposures or pathological conditions, including cancer (Bartkova et al, 2005;Nuciforo et al, 2007;Watters et al, 2009;Redon et al, 2011;Scarpato et al, 2011Scarpato et al, , 2013. The Zucker rat model offers a reliable genetic model for research on obesity and metabolic syndrome due to the incorporation of transgenic and knockout technology (Cozzi et al, 2009;Geurts et al, 2009).…”