A recent Yale study published in the Science journal has shed light on the role gut bacteria play in triggering autoimmune disease. In the study, bacteria from the small intestines of humans and mice have been shown to travel to other organs and drive autoimmune responses. These findings have led researchers to discover treatment pathways that could revolutionize the way autoimmune diseases -- diseases where the body's immune system attacks healthy tissues -- are treated.

What are gut bacteria and how do they affect autoimmune disease?

Gut Bacteria are species of naturally-occurring bacteria that are found in the intestines that play a big role in the digestion of food.

These bacteria are also thought to impact many health conditions such as depression, anxiety, obesity, heart disease and also, autoimmune diseases. Some of these bacteria are thought to play a protective role by curbing some of these conditions, while others, such as the species at the center of this study, Enterococcus gallinarum, are thought to play a role in driving disease.

Why was E.gallinarum the focus of the study?

E.gallinarum was the focus of this study because it had been observed to move outside the gut and into other organs such as the liver and spleen. When found outside the intestines of the mouse models that were studied, these bacteria were shown to cause the inflammation of organ tissue and drive the production of auto-antibodies, both of which are typical signs of an Autoimmune Response.

The same process of inflammation caused by these bacteria was found to occur in cultured liver cells from healthy human samples. These bacteria were also found in the livers of people with autoimmune disease.

What do these findings mean for potential treatment approaches?

The research team found that the autoimmune responses in mice were suppressed by antibiotics or a vaccine that targeted E.gallinarum.

Both approaches halted the growth of the bacteria in the affected tissues which led to the reduction of autoimmunity in the mice. In a Yale University news release, the senior author of the study, Martin Kriegel, M.D., called the use of the vaccine in the study a "specific approach," as he said that vaccines targetting the other bacteria investigated in the study were not effective in preventing autoimmunity or death.

The vaccine was administered by intramuscular injection to avoid interference with other gut bacteria. Kriegel and other members of the research team said that these findings "have relevance" to systemic lupus and autoimmune liver disease. Although research into E.gallinarum and its effects will continue, Kriegel said that treatments with antibiotics and vaccines promise ways to improve the lives of people affected by autoimmune disease.