Could a Tuberculosis vaccine reverse Type 1 diabetes?

By Lisa Foster-McNulty, MSN, RN, CDE

At the American Diabetes Association‘s 75th Scientific Sessions in Boston in June, researchers presented data showing real promise.  The vaccine bacillus Calmette-Guerin (BCG) was tested in a clinical trial, and interim results reveal a potential new pathway whereby the BCG vaccine might restore immune response to the insulin producing cells of the pancreas.  Denise Faustman, MD, PhD is the director of the Massachusetts General Hospital Immunobiology Laboratory, and she is the principle investigator of the clinical trial.  Research findings indicate that BCG could produce a permanent increase in gene expression which leads to restoration of the helpful regulatory T cells, called Tregs.  This prevents the body’s immune system from mistakenly attacking the body’s own healthy tissues. 

In Type 1 diabetes, islet cells are destroyed by autoreactive T cells because they mistakenly attack islets as they would attack an infection.  Tregs prevent this misguided attack against tissues without blunting the entire immune system.  While multiple research groups have indicated interventions to introduce or increase Tregs in patients with Type 1 diabetes, we currently don’t have any approved therapies.

BCG is FDA approved for vaccination against tuberculosis and for treating bladder cancer.  Throughout the world, research is being conducted to evaluate whether repeat BCG vaccinations could prevent and reverse autoimmune diseases including Type 1 diabetes and multiple sclerosis.

Worldwide,  other researchers are also investigating the BCG vaccination’s ability to reverse autoimmunity.  It has been understood for awhile now that restoring the helpful Treg cells could stop the abnormal self-reactivity of autoimmune diseases such as Type 1 diabetes.  Unfortunately, therapies designed to reinstate immune balance just haven’t been able to deliver long-lasting results.  Epigenetics is a mechanism that influences whether or not gene expression occurs.  That BCG provides restoration of Tregs through epigenetics is fascinating information.  The research enhances our understanding of how the BCG vaccine seems to modulate Treg induction, influencing the immune system to stop the underlying cause of the disease. 

BCG is of great interest since it seems to permanently activate Treg genes.  It is amazing that such a safe and cost-effective vaccination could potentially reverse serious chronic diseases. 

At the 75th Scientific Sessions, Faustman and colleagues announced the start of their phase 2 clinical trial, which will examine whether repeated BCG injections could be a treatment for Type 1 diabetes.  Previous research showed that advanced Type 1 diabetes could be reversed in mice, and a subsequent 20 week long phase 1 clinical trial on the use of BCG in humans is complete.  Phase 1 participants were randomized to get either two BGC vaccinations or a placebo.  In the treatment group, subjects experienced a short-lived eradication of diabetes-causing T cells, and a temporary restoration of insulin secretion.

The phase 2 trial will be conducted on 150 adults between the ages of 18 and 60.  It will be randomized and double-blinded.  Two injections of either BCG vaccine or placebo will be given two weeks apart, followed by one injection given annually for the next four years.  Blood tests will be done approximately every two weeks at first, eventually tapering down to every 6-12 months.  The researchers theory is that each BCG injection will eliminate increasing amounts of the disease-causing white blood cells.  The result is expected to be longer survival of insulin-producing cells in the pancreas, leading to a more sustained effect of insulin secretion. 

Thus far, this research holds a great deal of promise.  If the BCG vaccine can halt the body’s attack on itself and restore natural insulin secretion on a permanent basis, this would represent the kind of cure that we’ve all been praying for!