Diverse FOXP3 Expression in Children with Type 1 Diabetes and Celiac Disease

Imbalance between different types of T lymphocytes, such as T helper (Th) and regulatory T cells (Tregs), has been reported to play a part in the pathogenesis behind such autoimmune diseases as type 1 diabetes (T1D) and celiac disease (CD). Defects in Tregs are proposed to at least partly explain the imbalance of Th cells found in children with immunologic diseases. Peripheral blood mononuclear cells from 24 children with T1D and/or CD, and reference children (that is, those without any of these diseases) were stimulated with disease‐associated antigens (insulin, gluten, transglutaminase [tTG]), and phytohemagglutinin (PHA). The mRNA expression of the Treg‐associated marker FOXP3 was analyzed with multiplex real‐time RT‐PCR. Children with T1D showed both a low spontaneous (P < 0.05) and PHA‐induced (P < 0.01) expression of FOXP3 mRNA compared to children with CD. Children with T1D also had a low PHA‐induced FOXP3 mRNA expression compared to the group of children diagnosed with both T1D and CD (P < 0.05). Spontaneous (P < 0.05) and PHA‐induced (P < 0.05) FOXP3 mRNA expression was high in children with CD compared to reference children. In contrast, stimulation with insulin tended to induce high FOXP3 mRNA expression in T1D children compared to reference children (P= 0.057). In conclusion, children with only T1D generally showed a lower FOXP3 mRNA expression than did children with CD, or with T1D in combination with CD, which suggests impaired regulation of the immune system in children with T1D.