With this subject we are only talking about
Type 1 diabetes whose basis is an immune destruction of the insulin producing beta cells of the pancreas. A
diabetes vaccine to prevent this process sounds a very attractive idea. Preliminary results from several clinical trials have already been published. However, before getting too excited we should first explore all the difficulties and complications that are associated with this experimental treatment.
Type 1 diabetes is classified as an
autoimmune disease. This means that the root cause is that person's own
immune system. Our
immune cells usually provide us with the essential property of healing damage in our body and defending ourselves from attack by such things as viruses and bacteria. When our
immune cells parade around our body on guard they recognize our own cells as belonging to ourselves and leave them alone.
In
autoimmune diseases the
immune system falsely thinks our own cells are foreign or in some ways dangerous and begin an attack of destruction.
Type 1 diabetes occurs when this happens to the
beta cells of the pancreas. The trigger for such an attack is unknown. Researchers have tested many different processes but have not so far come up with a satisfactory answer.
In theory, arresting the
inflammatory autoimmune process could stop
beta cell destruction. The objective is quite clear but the problem is how to achieve it safely. Pioneering trials using the
oral immunosuppressant drug
cyclosporine was relatively successful. It halted the process leading to
beta cell loss. Destruction of the cells resumed, however, when the drug treatment ended. Moreover the
potential toxicity of prolonged treatment with
general immunosuppressive therapy has prohibited its use in
Type 1 diabetes.
Current research is focused on stopping the
autoimmunity in a more specific and direct way.
Vaccines are being developed which are able to modify the
immune response and shut down its destructive element.
Producing what is called
immune tolerance has been the basis of clinical trials and involves giving people preparations which regulate the
autoimmune response. In some of these the so-called
vaccine have included
insulin itself and in others a
pancreatic protein called
GAD.
A promising avenue of research has focused on a vaccine containing a fragment of a
protein known as
heat shock protein, which seems to direct the activity of the
immune system away from destroying the pancreas and towards preserving it. International clinical trials in this area are currently being undertaken.
So what does the future hold in this fascinating but complicated field of diabetes research? People in a
pre-diabetic state who are high risk for developing diabetes will more likely be the target for
diabetes vaccines because they still have ample
beta cell reserves. Current trials involve patients with recent onset
Type 1 diabetes and who may only have a small amount of functioning beta cells remaining. As with
vaccines against
bacterial or
viral infections,
vaccines would be more appropriate if they were given before the onset of the disease.
Multi-targeted
vaccines directed against a range of
beta cell antigens as well as individual patient tailored
vaccines will probably be one of the future keys to prevent
autoimmune Type 1 diabetes. It should also be remembered that meddling with some of the cells of the
immune system is a highly controversial area in clinical medicine and poses many questions regarding long-term safety.
One should beware therefore of media hype suggesting that we are on the threshold of launching a
vaccine for Type 1 diabetes because at the moment we are not anywhere near that point.