ST8Sia6 overexpression protects pancreatic β cells from spontaneous autoimmune diabetes in nonobese diabetic mice
Justin Choe, Paul Belmonte, Sydney Crotts, Thanh Nguyen, David Friedman, Alexi Zastrow, Matthew Rajcula, Brady Hammer, Claire Wilhelm, Michael J. Shapiro, Aleksey Matveyenko, Virginia Smith Shapiro
Justin Choe, Paul Belmonte, Sydney Crotts, Thanh Nguyen, David Friedman, Alexi Zastrow, Matthew Rajcula, Brady Hammer, Claire Wilhelm, Michael J. Shapiro, Aleksey Matveyenko, Virginia Smith Shapiro
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Research Article Autoimmunity Immunology

ST8Sia6 overexpression protects pancreatic β cells from spontaneous autoimmune diabetes in nonobese diabetic mice

Abstract

Type 1 diabetes is characterized by the autoimmune destruction of pancreatic β cells, resulting in permanent loss of glucose homeostasis. Islet transplantation is a promising potential cure that remains hindered by immune rejection. We previously showed that ST8Sia6 expression on tumors reduced immune surveillance and hypothesized that this sialyltransferase could protect β cells from autoimmune destruction. Here, we demonstrate that ectopic expression of ST8Sia6 in β cells of female nonobese diabetic mice (NOD βST) decreased the spontaneous incidence of diabetes by 90% and preserved β cell mass. NOD βST mice had comparable insulitis at 8 weeks of age that did not progress over time compared with littermate controls. β Cell–autoreactive B and T cells were present in NOD βST mice, indicating a peripheral rather than central mechanism of immune tolerance. The islets of NOD βST mice displayed a dampened type 1 immune response and reduced IL-12p35 expression in dendritic cells compared with those of littermate controls. The peripheral protection persisted even after removal of ST8Sia6 expression at 20 weeks of age, indicating that transient expression was sufficient for establishment of tolerance. These results demonstrate that ST8Sia6 protects β cells from immune-mediated attack and rejection, highlighting its therapeutic potential for autoimmune disorders.

Authors

Justin Choe, Paul Belmonte, Sydney Crotts, Thanh Nguyen, David Friedman, Alexi Zastrow, Matthew Rajcula, Brady Hammer, Claire Wilhelm, Michael J. Shapiro, Aleksey Matveyenko, Virginia Smith Shapiro

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Figure 4

βST mice have a reduction in the type 1 immune response in the islet.

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βST mice have a reduction in the type 1 immune response in the islet. (A...
(A–C) Representative flow cytometry plots of immune cells (A), short-lived effector CD8+ T cells (SLECs) (B), and CD4+ T cell subsets (C) in islets from euglycemic NOD βST or littermate mice at 14 weeks of age. Cells were previously gated by size and singlets. Within the live singlet CD45+TCRβ+CD4+ cell population, Th1 cells (FoxP3–T-bet+), Th17 cells (FoxP3–RORγt+), and Tregs (parsed by T-bet+ and T-bet–) were analyzed. SLECs were defined as T-bet+ cells within the live singlet CD45+TCRβ+CD8+ cell population. (D) Quantification of normalized event count of cells depicted in A. The number of each cell type was normalized to the number of cells per islet per mouse from 5 NOD βST or 14 littermates. (E) Quantification of frequency and normalized cell count of SLECs per islet isolated per mouse. One NOD βST mouse was censored because of lack of insulitis. (F) Quantification of frequency and normalized cell count of CD4+ T cell subsets per islet from C isolated per mouse; one NOD βST mouse was censored because of lack of insulitis. (G) Ratio of T-bet+ Tregs (T-bet+FoxP3+CD4+) to Th1 T cells (T-bet+FoxP3–CD4+) from the islets of euglycemic NOD βST or NOD littermate mice at 14 weeks as above and 20 weeks of age (7 NOD βST or 14 littermate mice). (H) Ratio of T-bet+ Tregs (T-bet+FoxP3+CD4+) to SLECs (T-bet+CD8+) from the islets of NOD βST or NOD littermate mice as in G. (I and J) Quantification of PD-1 and PD-L1 expression in CD4+ T cell subsets (I) and SLECs (J) from 4 NOD βST or 5 littermates. Error bars represent SD. Mann-Whitney U tests were used to examine statistical differences between groups.