Tai McCaddens Presentation of: Control of Autoimmune Diabetes in NOD Mice by GAD Expression or Suppr

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Tai McCaddens Presentation of Control of
Autoimmune Diabetes in NOD Mice by GAD Expression
or Suppression in ß Cells

• Ji-Won Yoon, Chang-Soon Yoon, Hye-Won Lim, Qi
  Quan Huang, Yup Kang, Kwang Ho Pyun, Kensuke
  Hirasawa, Robert S. Sherwin, Hee-Sook Jun

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PURPOSE OF STUDY

• KEY TERMS
• Type 1 or insulin-dependent diabetes mellitus
• Glutamic acid decarboxylase (GAD)
• Nonobese diabetic (NOD) mice
• Pancreatic B cells

• To determine if the suppression of GAD expression
  in NOD mice B cells will prevent diabetes.

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The incorporation of an antisense GAD transgene
into the NOD mice.
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Identifying six lines of antisense GAD transgenic
NOD mice based on the transgenes expression
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A Northern Blot of transgene negative, low,
medium, and high antisense transgene expressed RNA
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Protein Immunoblot of suppressed GAD expression
of high, medium, and low antisense transgene
lines in pancreatic and brain cells
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Stained pancreatic islets
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Conclusions Drawn

• Six lines of antisense GAD mice were established
• Of the six lines, GAD expression was completely
  suppressed in the pancreatic beta cells of the
  HIGH line transgenic mice.
• GAD was expressed in the brain cells of all of
  the transgenic lines.
• High line NOD mice are beta cell specific for
  suppressed GAD expression.
• Immunohistochemical staining of tissues confirmed
  that insulin content in the pancreas and plasma
  were similar for all of the transgenic lines.

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But is GAD expression in beta cells required in
order for autoimmune diabetes to develop in the
NOD mice?
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Measurement of the incidence of diabetes and
insulitis in the High, Medium, Low, and Transgene
Negative NOD mice up to 40 weeks of age
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When measured at 20 weeks, most of the pancreatic
islets of the H-AS-GAD-NOD mice remained intact,
in contrast to the other lines.
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Similar data for the Hk, Mk, and Lk antisense NOD
mice
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Conclusion

• GAD expression in beta cells is required in order
  for diabetes to develop

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..But was it due to the incorporation of the
antisense transgene into the cDNA?

• Mice containing an incorporated endogenous
  retroviral env protein, another beta cell
  autoantigen like GAD, were created.
• These mice all developed diabetes, even in the
  highly expressed mice.
• It was thus concluded that the incorporation of
  the antisense transgene did not affect the
  prevention of diabetes in the GAD mice.

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Are only pancreatic beta cells affected by the
suppression of GAD expression?

• The Salivary glands were examined, and
  lymphocytic infiltration resulted.

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Is the reason that diabetes does not develop in
suppressed GAD-expressed beta cells due to the
blocking of beta cell-specific diabetogenic T
cells?
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Measurement of the incidence of diabetes in the
Transgene Negative, High, and Diabetic NOD of
NOD.scid mice
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Do the T cells of other beta cell autoantigens
proliferate in response to suppressed GAD
expression?
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Are GAD-suppressed beta cells more susceptible to
attack by diabetogenic T cells when transplanted
into diabetic NOD mice?
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Blood glucose levels of transplanted
GAD-suppressed H-AS-GAD-NOD mice islets and
GAD-expressed transgene negative NOD mice islets
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Incidence of diabetes of transferred H-AS-GAD-NOD
and transgene negative mice
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Insulitis Examination
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As a result, it was concluded that..

• The resistance of GAD transgenic NOD islets to T
  cell proliferation is specific.
• Autoimmune destruction of beta cells results when
  GAD is expressed.

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And finally it was overall concluded that.

• In order for diabetogenic T cells to proliferate,
  GAD expression is needed.
• Without the expression GAD in the beta cells,
  diabetes can not be provoked in NOD mice.

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REFERENCE

• Control of Autoimmune Diabetes in NOD Mice by GAD
  Expression or Suppression in B cells, Yoon et.
  Science, May 14, 1999, vol. 284.