Uncoupling of Proliferation and Cytokines From Suppression Within the CD4+CD25+Foxp3+ T–Cell Compartment in the 1st Year of Human Type 1 Diabetes

  1. Deborah J. Fowell1
  1. 1David H. Smith Center for Vaccine Biology and Immunology, Aab Institute of Biomedical Sciences, Department of Microbiology and Immunology, University of Rochester, Rochester, New York
  2. 2Division of Pediatric Endocrinology, University of Rochester Medical School, Rochester, New York
  3. 3Human Immunology Center, David H. Smith Center for Vaccine Biology and Immunology, University of Rochester Medical School, Rochester, New York
  1. Corresponding author: Deborah J. Fowell, deborah_fowell{at}urmc.rochester.edu
  1. A.H. and I.B. contributed equally to this study.

Abstract

OBJECTIVE The mechanistic basis for the breakdown of T-cell tolerance in type 1 diabetes is unclear and could result from a gain of effector function and/or loss of regulatory function. In humans, the CD4+CD25+Foxp3+ T–cell compartment contains both effector and regulatory T cells, and it is not known how their relative proportions vary in disease states.

RESEARCH DESIGN AND METHODS We performed a longitudinal study of CD4+CD25+ T–cell function in children with type 1 diabetes at onset and throughout the 1st year of disease. Function was assessed using single-cell assays of proliferation, cytokine production, and suppression. Type 1 diabetic individuals were compared with age-matched control subjects, and suppression was directly assessed by coculture with control T–cell targets.

RESULTS We identify novel functional changes within the type 1 diabetes CD4+CD25+ compartment. Type 1 diabetic CD4+CD25+ cells exhibited a striking increase in proliferative capacity in coculture with CD4 T cells that was present at onset and stable 9–12 months from diagnosis. Elevated type 1 diabetes CD4+CD25+ cell proliferation correlated with increased inflammatory cytokines interleukin 17 and tumor necrosis factor-α but not γ-interferon. Type 1 diabetes CD4+CD25+ cytokine production occurred coincident with suppression of the same cytokines in the control targets. Indeed, enhanced proliferation/cytokines by CD4+CD25+ cells was uncoupled from their suppressive ability. Longitudinally, we observed a transient defect in type 1 diabetes CD4+CD25+ suppression that unexpectedly correlated with measures of improved metabolic function.

CONCLUSIONS Type 1 diabetes onset, and its subsequent remission period, is associated with two independent functional changes within the CD4+CD25+ T–cell compartment: a stable increase in effector function and a transient decrease in regulatory T–cell suppression.

Footnotes

  • Received November 30, 2010.
  • Accepted May 17, 2011.

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  1. Diabetes vol. 60 no. 8 2125-2133
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