In:
Diabetes, American Diabetes Association, Vol. 67, No. 7 ( 2018-07-01), p. 1356-1368
Kurzfassung:
In spite of tolerance mechanisms, some individuals develop T-cell–mediated autoimmunity. Posttranslational modifications that increase the affinity of epitope presentation and/or recognition represent one means through which self-tolerance mechanisms can be circumvented. We investigated T-cell recognition of peptides that correspond to modified β-cell antigens in subjects with type 1 diabetes. Modified peptides elicited enhanced proliferation by autoreactive T-cell clones. Endoplasmic reticulum (ER) stress in insulinoma cells increased cytosolic calcium and the activity of tissue transglutaminase 2 (tTG2). Furthermore, stressed human islets and insulinomas elicited effector responses from T cells specific for modified peptides, suggesting that ER stress–derived tTG2 activity generated deamidated neoepitopes that autoreactive T cells recognized. Patients with type 1 diabetes had large numbers of T cells specific for these epitopes in their peripheral blood. T cells with these specificities were also isolated from the pancreatic draining lymph nodes of cadaveric donors with established diabetes. Together, these results suggest that self-antigens are enzymatically modified in β-cells during ER stress, giving rise to modified epitopes that could serve to initiate autoimmunity or to further broaden the antigenic repertoire, activating potentially pathogenic CD4+ T cells that may not be effectively eliminated by negative selection.
Materialart:
Online-Ressource
ISSN:
0012-1797
,
1939-327X
Sprache:
Englisch
Verlag:
American Diabetes Association
Publikationsdatum:
2018
ZDB Id:
1501252-9
