BCG Vaccine May Reverse Type 1 Diabetes

A clinical trial testing the generic vaccine bacillus Calmette-Guérin (BCG) to reverse advanced type 1 diabetes demonstrated a potential to restore the proper immune response to the insulin-secreting, islet cells of the pancreas.

Presented by Denise Faustman, MD, PhD, director of the Massachusetts General Hospital Immunobiology Laboratory and principal investigator of the trial, this clinical trial finding suggests that BCG may induce a permanent increase in expression of genes that restore the beneficial regulatory T cells (Tregs).

Tregs prevent the immune system from attacking the body's own tissue.

Dr. Faustman, said "We and other global efforts have known for some time that restoring beneficial Treg cells might halt the abnormal self-reactivity in type 1 diabetes and other autoimmune diseases, but therapies to restore this immune balance have not achieved long-lasting results.”

“The discovery that BCG restores Tregs through epigenetics - a process that modulates whether or not genes are expressed - is exciting - and resetting the immune system to halt the underlying cause of the disease."

BCG, or bacille Calmette-Guerin, is a vaccine for tuberculosis (TB) disease.

BCG is used in many countries with a high prevalence of TB to prevent childhood tuberculous meningitis and miliary disease.

However, BCG is not generally recommended for use in the United States because of the low risk of infection with Mycobacterium tuberculosis, the variable effectiveness of the vaccine against adult pulmonary TB, and the vaccine’s potential interference with tuberculin skin test reactivity.

The BCG vaccine should be considered only for very select persons who meet specific criteria and in consultation with a TB expert.

The bacille Calmette-Guérin (BCG) vaccine has existed for 80 years and is one of the most widely used of all current vaccines.

Type 1 diabetes is an autoimmune disease characterized by the destruction of islets by autoreactive T cells, which mistakenly attack islets as if they were an infection. Tregs are the immune system's "brakes" that normally prevent misdirected attacks against tissues without dampening the entire system. Several research groups have suggested methods for introducing or expanding Tregs in patients with type 1 diabetes, but to date no therapies have been approved.

Dr. Faustman said, "Repeat BCG vaccination appears to permanently turn on signature Treg genes, and the vaccine's beneficial effect on host immune response recapitulates decades of human co-evolution with myocbacteria, a relationship that has been lost with modern eating and living habits. It is incredible that a safe and inexpensive vaccine may be the key to stopping these terrible diseases."

The five-year, 150-person, phase II trial is investigating whether repeat BCG vaccination can clinically improve type 1 diabetes in adults with existing disease and is almost fully enrolled.

Details on the trial and enrollment are available here.