FOXP3, IL-10, and TGF-β Genes Expression in Children with IgE-Dependent Food Allergy

Regulatory T cells (Tregs) have an essential role in tolerance and immune regulation. However, few and controversial data have been published to date on the role and number of these cells in food allergic children. The forkhead/winged-helix transcription factor box protein 3 (FOXP3) is considered the most reliable marker for Tregs. This study aims to investigate the FOXP3, interleukin (IL)-10, and transforming growth factor (TGF-beta) genes expression in children with IgE-dependent food allergy. The study group consisted of 54 children with IgE-dependent food allergy (FA) and a control group of 26 non-atopic healthy children. The diagnosis of FA was established using questionnaires, clinical criteria, skin prick tests, serum sIgE antibodies (UniCAP 100 Pharmacia Upjohn), and a double-blind placebo control food challenge. In order to assess gene expression, the isolation of nucleated cells was performed using Histopaque-1077 (Sigma-Aldrich, Germany). The concentration of RNA obtained was measured using a super-sensitive NanoDrop ND1000 spectrophotometer (Thermo Scientific, USA). A reverse transcription reaction was performed using a commercially available set of High Capacity cDNA Archive Kit (Applied Biosystems, USA). Analysis have been carried out in the genetic analyzer 7900HT Real-Time PCR (Applied Biosystems, USA). The average level of the FOXP3 gene expression in the studied group was 2.19 +/- 1.16 and in the control group 2.88 +/- 1.66 (p = 0.03). The average level of IL10 mRNA expression in the study group was 13.6 +/- 1.07 and was significantly lower than corresponding values in the control group 14.3 +/- 1.1 (p = 0.01). There were no significant differences in the average level of the TGF-beta mRNA expression in the study group (3.4 +/- 0.4) and controls (3.5 +/- 0.3; p > 0.05). The FOXP3 gene expression was the highest in children who acquired tolerance to food (3.54 +/- 0.75), lower in heated allergen-tolerant children (2.43 +/- 0.81), and the lowest in heated allergen-reactive children (1.18 +/- 0.5; p = 0.001 control vs heated allergen reactive; p = 0.005 heated allergen tolerant vs heated allergen reactive; p = 0.001 outgrown vs heated allergen reactive). The significant tendency toward lower total IgE levels with a higher FOXP3 mRNA expression was detected (n = 54; Pearson r = -0.4393; p = 0.001). Children with FA showed statistically significant lower level of the FOXP3 and IL10 gene expression than healthy children. Children acquiring tolerance to the food show significantly higher levels of the FOXP3 gene expression than children with active FA. The correlation between the level of FOXP3 and total IgE was detected.