Type I diabetes might be reversed with the BCG vaccine, suggests new findings presented at the 75th Scientific Sessions of the American Diabetes Association.
The vaccine known as bacillus Calmette-Guérin (BCG) has been tested on type I diabetes in an FDA-approved clinical trial. Diabetes type I, unlike diabetes type II, is an autoimmune disease whereby cells of the immune system, the autoreactive T cells, kill the insulin-producing cells of the pancreas (islets of Langerhans). T cells normally function to fight infection; they get rid of harmful foreign bodies. However, in this disease, they target the body’s own cells. This unwanted attacked should have normally been stopped by beneficial regulatory T cells (Tregs) of the immune system; these cells are known to preventing the immune system from attacking the body’s own cells. Thankfully, though, it appears that BCG vaccine might be the one to stop the autoimmune reaction.
The new findings show that the vaccine might restore the correct immune response with respect to the pancreas cells: BCG might be triggering a permanent boost in the expression of genes that code for Tregs which, then, prevent the immune system from attacking the body’s own cells; the mechanism, thus, appears to be based on epigenetics, the process that regulates the expression of genes (which gene is switched on, and which one is turned off).
According to study author, Denise Faustman from Harvard Medical School, other researchers are investigating the ability of BCG vaccine at reversing autoimmunity. Now, with the new study, it is known that BCG brings back Tregs through epigenetics, thereby possibly paving the way to new therapies to be developed based on this knowledge. Faustman explains that the new findings give “a better idea of how BCG vaccination appears to work by powerfully modulating Treg induction and resetting the immune system to halt the underlying cause of the disease”. Furthermore, previous attempts at introducing Tregs in type I diabetes patients have been unproductive, hence BCG is hailed as the possible solution.
BCG is, otherwise, used to prevent tuberculosis. It is made from a harmless relative of the tuberculosis bacterium. Used for years now, it is FDA-approved, and has also been used to treat bladder cancer.
“BCG is interesting because it brings into play so many areas of immunology that we as a community have been looking at for decades, including Tregs and the hygiene hypothesis,” says Faustman. “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.”
Findings from a follow-up study will be published later this year.