Expansion of CD4+CD25+FOXP3+ regulatory T cells in infants of mothers with type 1 diabetes

• Published in: Pediatric diabetes Vol. 13; no. 5; pp. 400 - 407
• Main Authors: Luopajärvi, Kristiina, Nieminen, Janne K, Ilonen, Jorma, Åkerblom, Hans K, Knip, Mikael, Vaarala, Outi
• Format: Journal Article
• Language: English
• Published: Denmark Blackwell Publishing Ltd 01.08.2012
• Subjects: CD25 antigen; CD4 antigen; CD4 Antigens - blood; Children; Cord blood; Diabetes mellitus; Diabetes Mellitus, Type 1 - drug therapy; Diabetes Mellitus, Type 1 - immunology; Female; Fetal Blood - immunology; Fetuses; Flow cytometry; Forkhead Transcription Factors - blood; Foxp3 protein; Gene expression; Humans; Immunoregulation; Infant; Infant, Newborn; Infants; Insulin; Insulin - therapeutic use; insulin treatment; Interleukin 10; Interleukin-2 Receptor alpha Subunit - blood; Leukocytes (mononuclear); Lymphocytes T; Male; Mothers; Polymerase chain reaction; Progeny; Protein-tyrosine-phosphatase; regulatory T cells; Reverse transcription; Risk factors; STIM1 protein; T-Lymphocytes, Regulatory - immunology; T1D; Transforming growth factor; Transforming growth factor- beta
• ISSN: 1399-543X; 1399-5448; 1399-5448
• DOI: 10.1111/j.1399-5448.2012.00852.x

Background Reduced risk for type 1 diabetes (T1D) has been reported in the offspring of mothers with T1D when compared with children of affected fathers. Objective To evaluate the hypothesis that exposure of the offspring to maternal insulin therapy induces regulatory mechanisms in utero, we compared the FOXP3 expressing regulatory T cells in cord blood (CB) of infants born to mothers with or without T1D. Subjects and Methods Cord blood mononuclear cells (CBMCs) from 20 infants with maternal T1D and from 20 infants with an unaffected mother were analyzed for the numbers of CD4+CD25+FOXP3+ cells ex vivo and after in vitro stimulation with human insulin by flow cytometry. The mRNA expression of FOXP3, NFATc2, STIM1, interleukin (IL)‐10, and transforming growth factor (TGF)‐β was measured by real‐time reverse transcription polymerase chain reaction. Results The percentage of FOXP3+ cells in CD4+CD25high cells was higher in the CB of the infants with maternal T1D when compared with the infants of unaffected mothers (p = 0.023). After in vitro insulin stimulation an increase in the percentage of FOXP3+ cells in CD4+CD25high cells (p = 0.0002) as well as upregulation of FOXP3, NFATc2, STIM1, IL‐10, and TGF‐β transcripts in CBMCs (p < 0.013 for all; Wilcoxon test) was observed only in the offspring of mothers with T1D, in whom the disease‐related PTPN22 allele was associated with reduced STIM1 and NFATc2 response in insulin‐stimulated CBMCs (p = 0.007 and p = 0.014). Conclusions We suggest that maternal insulin treatment induces expansion of regulatory T cells in the fetus, which might contribute to the lower risk of diabetes in children with maternal vs. paternal diabetes.