The Expression of GAD in Beta Cells of NOD Mice is Required for the Development of Diabetes

1. The Expression of GAD in Beta Cells of NOD Mice is Required for the Development of Diabetes Susannah A. Hill

2. Background • Diabetes is an autoimmune disease • Diabetes my be prevented by suppressing an autoimmune response

3. Control of Autoimmune Diabetes in NOD Mice by GAD Expression or Suppression in Beta Cells Yoon et al. 1999

4. Glutamic Acid DecarboxylaseGAD is a protein produced by beta islet cells

5. A Six Part Study • The expression of GAD is required to develop diabetes • The suppression of GAD is specific • GAD’s action is specific to the beta cell • GAD acts via diabetogenic T cells • Other B cell autoantigen-specific T cells are dependant upon GAD • GAD suppressed/expressing B cell grafts

6. The expression of antisense GAD was quantitated with a Southern blot

7. Histological examination of islets in high, medium, low, and transgene-negative islets

8. Conclusion These data are indicative of a GAD-dependant response

9. The expression of GAD is required to develop diabetes • Highly anti-GAD transgenic NOD mice did not develop diabetes • Moderate and low amounts of transgene prevented diabetes by 33% and 25% respectively • Conclusion: Beta cell GAD expression is required for the development of diabetes

10. The incidence of diabetes at various ages is shown

11. The suppression of GAD is specific • Transgenic mice infected with a viral DNA developed diabetes • Transgene-negative mice infected with viral DNA also developed diabetes • Conclusion: The prevention of diabetes in transgenic mice is not due to the nonspecific effect of an antisense transgene

12. GAD’s action is specific to the beta cell • Diabetogenic T cells were able to infiltrate into the salivary gland of highly transgenic mice • Conclusion: Autoimmunity is specific to beta cells

13. The difference between islet cells of transgenic (GAD) and transgene-negative lines

14. The salivary gland cells in both transgenic and transgene-negative mouse lines

15. GAD acts via diabetogenic T cells • 0% of mice receiving splenocytes from highly transgenic mice developed diabetes • 90% of mice receiving splenocytes from transgene- negative mice developed diabetes • Conclusion: GAD expression is required for the generation of diabetogenic T cells

16. Other beta cell autoantigen-specific T cells are dependant upon GAD • Immunization of NOD mice with GAD suppresses T cell responses to GAD, heat shock protein 60, carboxypeptidase H, and peripherin • Conclusion: The suppression of GAD prevents immune responses of other auto- antigens as well as GAD

17. The splenic T cell proliferative response to other islet auto-antigens

18. The resilience of GAD-suppressed beta cells to attack by grafted diabetogenic T cells • 0% of mice receiving GAD-suppressed islets developed diabetes • 100% of recipients of GAD-expressing islets developed diabetes • Transplanting env-(an antisense proviral DNA), caused islet destruction

19. The effect of GAD suppressed and expressing islet grafts on blood glucose levels in NOD recipients

20. Antisense vs. Tg- cells

21. Conclusions • The expression of GAD is required to develop type 1 diabetes in the NOD mouse • The resistance of GAD suppressed islets is a specific effect • GAD expression is neccessary for the induction of diabetogenic T cells • These CD4+ and CD8+ T cells cannot act without GAD