Can a vaccine prevent type 1 diabetes?

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Type 1 diabetes is an autoimmune disease in which the body’s immune system attacks the body’s own components, resulting ultimately in the stress and death of insulin-producing beta cells in the pancreas. The exact impetus for the autoimmune breakdown is unclear, but the theory goes something like:

  1. For some reason, the immune system becomes sensitized against pancreatic beta cell proteins like insulin and the enzyme GAD65, to which it makes antibodies (An antibody is a special protein released by the immune system that is designed to target and disable invading pathogens like bacteria and viruses; an autoantibody, then, is an antibody directed towards the self.)
  2. This internal immune struggle against individual proteins expands, resulting in a very inflammatory environment in the tissues of the pancreas.
  3. The stress is too much for beta cells, and they undergo apoptosis, or cell death.
  4. As the beta cells die off, the body loses its ability to produce insulin.  The result is diabetes.

If this is the general progression of type 1 diabetes, then it stands to reason that ameliorating the initial inflammatory reaction– against insulin, GAD65 and so on– could help prevent the gradual increase of inflammation and ultimate beta cell apoptosis.  Thus, a number of researchers, including Leonard C. Harrison at the Walter and Eliza Hall Institute of Medical Research in Victoria, Australia, have been investigating the possibility that type 1 diabetes can be stopped in its early pre-clinical stage.

How does one prevent the immune system attack on these proteins? The general idea is a kind of reverse-vaccine: inundate the body with the protein of interest in a particular way, and the immune system will be normalized, accepting the protein as self rather than foreign invader.

A number of different approaches have been tried along this vein, with different proteins and different means of administration, but Harrison and his team have focused on nasal administration of the insulin protein. After seeing the success in mice of insulin administration, Harrison conducted a trial in which insulin was administered nasally to 52 recent-onset type 1 diabetics. Unfortunately, the treatment did not prevent or significantly slow the death of beta cells in the participants. However, the treatment did desensitize the immune system so that when insulin was later injected the amount of antibodies made to the injected insulin was significantly reduced.

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