Retardation or acceleration of diabetes in NOD/Lt mice mediated by intrathymic administration of candidate beta-cell antigens.
A single injection of syngeneic islet cells into the thymus of 4-week-old NOD/Lt female mice strongly retards diabetogenesis. The present study used the intrathymic route of antigen administration to compare the relative efficacy of peptides/proteins derived from two major candidate pancreatic beta-cell autoantigens, insulin and GAD65, to modulate diabetogenesis. Intrathymic administration of insulin B chain or recombinant human GAD65 significantly suppressed diabetogenesis during a 20-week follow-up period, whereas no protection was mediated by either insulin A chain or a synthetic peptide (A2) derived from it. Quite unexpectedly, two GAD65-derived peptides near the COOH-terminus (p34 and p35) accelerated diabetes onset. Semiquantitative reverse transcription-polymerase chain reaction analysis was performed on cDNAs from isolated islets or whole pancreases of NOD/Lt females 4 weeks after intrathymic injections. Protection mediated by intrathymic administration with either intact islet cells or GAD65 were correlated with an upregulation of mRNA for T-helper 2 (Th2)-associated cytokines (interleukin [IL]-4, IL-10), concomitant with downregulation of Th1-associated interferon (IFN) transcripts (all normalized to T-cell receptor Cbeta transcripts) in islet-infiltrating lymphocytes. Protection mediated by the intrathymic administration of insulin B chain, however, correlated only with a modest upregulation of IL-4 and IL-10 transcript levels, and no diminution in IFN-gamma transcripts. In contrast, the diabetes-accelerating GAD65 p34 and p35 peptides were not associated with an immune deviation, expressing levels of IFN-gamma characteristic of islet-infiltrating lymphocytes in vehicle-injected NOD controls. Hence, Th1-to-Th2 immune deviation provides only a partial explanation for peptide immunotherapy of diabetes in NOD mice. The finding that certain peptides can accelerate rather than retard diabetogenesis as a function of route and age of administration adds a cautionary note to this type of therapy.
Cetkovic-Cvrlje
M
M
The Jackson Laboratory, Bar Harbor, Maine 04609, USA.
Gerling
I C
IC
Muir
A
A
Atkinson
M A
MA
Elliott
J F
JF
Leiter
E H
EH
D019264:Adoptive Transfer; D000595:Amino Acid Sequence; D000818:Animals; D001324:Autoantigens / Q000008:administration & dosage / Q000276:immunology*; D016207:Cytokines / Q000235:genetics; D003920:Diabetes Mellitus / Q000276:immunology / Q000517:prevention & control*; D005260:Female; D005968:Glutamate Decarboxylase / Q000008:administration & dosage / Q000276:immunology; D007328:Insulin / Q000008:administration & dosage / Q000276:immunology; D007515:Islets of Langerhans / Q000276:immunology*; D016381:Islets of Langerhans Transplantation; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000008:administration & dosage / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D013950:Thymus Gland / Q000276:immunology*
D001324:Autoantigens; D016207:Cytokines; D007328:Insulin; D010446:Peptide Fragments; D005968:Glutamate Decarboxylase