Regulatory T cell phenotype and function 4 years after GAD–alum treatment in children with type 1 diabetes

Authors

  • M. Pihl,

    Corresponding author
    • Division of Pediatrics, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University
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  • L. Åkerman,

    1. Division of Pediatrics, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University
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  • S. Axelsson,

    1. Division of Pediatrics, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University
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  • M. Chéramy,

    1. Division of Pediatrics, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University
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  • M. Hjorth,

    1. Division of Pediatrics, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University
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  • R. Mallone,

    1. INSERM, U986, DeAR Lab Avenir, Saint Vincent de Paul Hospital
    2. Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine
    3. Assistance Publique – Hopitaux de Paris, Hôpital Cochin et Hôtel Dieu, Service de Diabétologie, Paris, France
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  • J. Ludvigsson,

    1. Division of Pediatrics, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University
    2. Östergötland County Council, Linköping University Hospital, Linköping, Sweden
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  • R. Casas

    1. Division of Pediatrics, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University
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Correspondence: M. Pihl, Division of Pediatrics, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, SE-58185 Linköping, Sweden.

E-mail: mikael.pihl@liu.se

Summary

Glutamic acid decarboxylase (GAD)65 formulated with aluminium hydroxide (GAD-alum) was effective in preserving insulin secretion in a Phase II clinical trial in children and adolescents with recent-onset type 1 diabetes. In addition, GAD-alum treated patients increased CD4+CD25hi forkhead box protein 3+ (FoxP3+) cell numbers in response to in-vitro GAD65 stimulation. We have carried out a 4-year follow-up study of 59 of the original 70 patients to investigate long-term effects on the frequency and function of regulatory T cells after GAD-alum treatment. Peripheral blood mononuclear cells were stimulated in vitro with GAD65 for 7 days and expression of regulatory T cell markers was measured by flow cytometry. Regulatory T cells (CD4+CD25hiCD127lo) and effector T cells (CD4+CD25CD127+) were further sorted, expanded and used in suppression assays to assess regulatory T cell function after GAD-alum treatment. GAD-alum-treated patients displayed higher frequencies of in-vitro GAD65-induced CD4+CD25+CD127+ as well as CD4+CD25hiCD127lo and CD4+FoxP3+ cells compared to placebo. Moreover, GAD65 stimulation induced a population of CD4hi cells consisting mainly of CD25+CD127+, which was specific of GAD-alum-treated patients (16 of 25 versus one of 25 in placebo). Assessment of suppressive function in expanded regulatory T cells revealed no difference between GAD-alum- and placebo-treated individuals. Regulatory T cell frequency did not correlate with C-peptide secretion throughout the study. In conclusion, GAD-alum treatment induced both GAD65-reactive CD25+CD127+ and CD25hiCD127lo cells, but no difference in regulatory T cell function 4 years after GAD-alum treatment.

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