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 7

Tolerance from disease is established after 20 weeks.

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Tolerance from disease is established after 20 weeks. (A) Confirmation o...
(A) Confirmation of ST8Sia6-myc shutoff after 5 weeks of doxycycline treatment by IHC. Schematic of doxycycline treatment for temporal control of ST8Sia6 expression. Scale bars: 100 μm. (B) Diabetes-free incidence after treatment of 15 euglycemic NOD βST and 29 euglycemic littermate mice with doxycycline starting at 8 weeks of age. (C) Comparison with disease kinetics of 8-week-old euglycemic non-doxycycline-treated NOD βST (n = 50) or littermate (n = 151) mice (subset from Figure 1C). (D) Diabetes-free incidence after treatment of 12 euglycemic NOD βST and 16 euglycemic littermate mice with doxycycline starting at 20 weeks of age. (E) Comparison with disease kinetics of 20-week-old euglycemic non-doxycycline-treated NOD βST (n = 50) or littermate (n = 115) mice (subset from Figure 1C). Log-rank Mantel-Cox test was used to analyze statistical differences in diabetes-free incidence of indicated groups. (F) Insulitis distribution in pancreas sections of NOD βST mice treated with doxycycline for 5 weeks from 8 weeks or 20 weeks of age, compared with 300-day-old pancreata from NOD βST mice never treated with doxycycline (subset from Figure 1E). Scoring and analysis as in Figure 1E. n = 69 islets from 12 mice (8-week doxycycline) or 127 islets from 11 mice (20-week doxycycline). (G and H) Ratio of T-bet+ Tregs (T-bet+FoxP3+CD4+) to Th1 T cells (T-bet+FoxP3–CD4+) (G) or to SLECs (T-bet+CD8+) (H) from islets of 20-week-old mice treated with doxycycline for greater than 5 weeks. (I) Quantification of IL-12p35 expression in hybrid macrophages (CD11b+CD11c+F4/80+Gr1–) and cDC2s (CD11b+CD11c+F4/80–Gr1–) from islets of 20-week-old mice treated with doxycycline for greater than 5 weeks. Same gating schemes as in Figures 4 and 5. Error bars represent SD. Mann-Whitney U test was used for statistical analysis between groups.