Type 1 diabetes is an autoimmune disease involving T-cell autoreactivity against the insulin-producing β-cells of the pancreas, which results in dependence on exogenous insulin. Autoreactive CD8+ T-cells kill β-cells directly through MHC I-TCR interactions and perforin-granzyme release. Interferons, particularly interferon-γ, create an inflammatory pancreatic environment, regulate immune cell trafficking, and control β-cell antigen presentation to activated immune cells. Previous studies show that despite their role in these pathogenic processes, loss of interferon-γ or its receptor does not prevent diabetes in NOD mice.
In contrast, interferon receptor deficiency in the accelerated CD8+ T-cell transgenic NOD/8.3 model, in which over 90% of the CD8+ T-cells respond to the β-cell peptide IGRP206–214, results in significant protection from diabetes. Immunohistochemistry and flow cytometry shows delayed insulitis development and maintained β-cell mass despite aberrant T-cell expansion within the islets in NOD/8.3 mice lacking interferon receptors. This protection correlates with reduced MHC I expression on β-cells, dendritic cells, and inflammatory macrophages. The proportion of the latter population is decreased in the spleen and islets of interferon-receptor deficient NOD/8.3 mice, indicating an overall reduced ability to present β-cell antigens. Consequently, these mice have reduced proportions of CD44hi CD8+ T-cells in the spleen, indicating reduced antigen experience and increased expression of KLRG1 and PD-1 on antigen experienced CD8+ T-cells, suggestive of chronic antigen persistence.
Future work will use single cell RNA sequencing to determine how NOD mice, with a polyclonal T-cell repertoire, develop diabetes despite reduced antigen presentation due to interferon receptor deficiency. This research contributes to understanding pathogenic mechanisms in autoimmune diabetes, which is required to develop much-needed immunomodulatory therapies that prevent β-cell destruction.