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.