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(Journal Article): A sudden decline in active membrane-bound TGF-beta impairs both T regulatory cell function and protection against autoimmune diabetes.
Gregg RK, Jain R, Schoenleber SJ, Divekar R, Bell JJ, Lee HH, Yu P, Zaghouani H (Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, MO 65212, USA.)
IN:
J Immunol
2004; 173:7308-7316
Impact Factor(s) of J Immunol: 6.486 (2004), 6.702 (2003), 7.065 (2001)
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ABSTRACT: Autoimmunity presumably manifests as a consequence of a shortfall in the maintenance of peripheral tolerance by CD4(+)CD25(+) T regulatory cells (Tregs). However, the mechanism underlying the functional impairment of Tregs remains largely undefined. In this study a glutamic acid decarboxylase (GAD) diabetogenic epitope was expressed on an Ig to enhance tolerogenic function, and the resulting Ig-GAD expanded Tregs in both young and older insulitis-positive, nonobese diabetic (NOD) mice, but delayed autoimmune diabetes only in the former. Interestingly, Tregs induced at 4 wk of age had significant active membrane-bound TGF-beta (mTGF-beta) and sustained protection against diabetes, whereas Tregs expanded during insulitis had minimal mTGF-beta and could not protect against diabetes. The Tregs probably operate suppressive function through mTGF-beta, because Ab blockade of mTGF-beta nullifies protection against diabetes. Surprisingly, young Tregs that modulated pathogenic T cells maintained stable frequency over time in the protected animals, but decreased their mTGF-beta at the age of 8 wk. More strikingly, these 8-wk-old mTGF-beta-negative Tregs, which were previously protective, became unable to confer resistance against diabetes. Thus, a developmental decline in active mTGF-beta nullifies Treg function, leading to a break in tolerance and the onset of diabetes.
TYPE OF PUBLICATION: Original article
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