An estimated 50 million Americans ― that’s 20 percent of the general population ― suffer from autoimmune diseases like lupus, multiple sclerosis or rheumatoid arthritis, and many experts say that number is rising at an alarming rate.
Autoimmunity occurs when the immune system begins attacking the body’s healthy tissue as if it were an outside invader, leading to chronic inflammation. We still don’t know much about what causes the immune system to go haywire, or how to effectively treat it.
But new research suggests that the gut microbiome ― the community of trillions of “good” and “bad” bacteria living in the body’s intestinal tract ― could play a larger role than scientists have realized. Alterations in gut bacteria are one cause of the runaway inflammation characteristic of autoimmune conditions, according to a study slated for publication in the January issue of the Journal of Experimental Medicine.
Scientists already knew that the gut microbiome and the immune system are closely intertwined and constantly engaged in dynamic interaction. But new studies like this one continue to reveal more intricate connections between these two key systems of the body, including the ways that dysfunctions in both systems can contribute to autoimmunity.
“Beneficial gut bacteria promotes immune homeostasis, which means that resident gut bacteria have beneficial nutritional effects and the effect of reducing autoimmunity and inflammation,” Dr. Yuying Liu, a professor of pediatrics and gastroenterology at the University of Texas and the study’s lead author, told The Huffington Post.
In an experiment on mice, scientists at the university’s Health Science Center in Houston showed that increasing levels of a particular strain of healthy bacteria (also known as a probiotic) could “reset” the microbial community in the gut, thereby reducing inflammation. These “good” bacteria are a beneficial strain of the Lactobacillus family, other strains of which can be found in commercial probiotic supplements and fermented foods like yogurt and kefir.
Here’s how it works: The body contains “regulatory T cells.” Their job is to maintain balance within the immune system and prevent immune cells from getting so confused they accidentally attack the body’s own cells. Defective T reg cells cause chronic inflammation and autoimmune disease by altering the type of bacteria living in the gut, reducing levels of certain healthy bacteria.
But mice that were given healthy Lactobacillus bacteria had their microbial community go back to normal and saw reduced inflammation.
“Probiotics and probiotic-modulated microbiota … may represent a potential avenue for combatting autoimmune diseases mediated by T reg dysfunction,” Liu said.
The study revealed further links between gut bacteria and autoimmune disease, beyond T cell activity. Mice that carried a mutant version of a particular gene showed changes in gut bacteria ― specifically, lower levels of bacteria from the genus Lactobacillus ― at roughly the same time that they began exhibiting autoimmune symptoms, the researchers found.
These findings add weight to the idea that dietary and lifestyle interventions may be a powerful way to treat autoimmune diseases ― conditions for which conventional treatments are often ineffective and come with many side effects. The beneficial effects of probiotics on the immune system may be one reason why (anecdotally, at least) autoimmune conditions seem particularly responsive to dietary changes as a form of complementary treatment. In fact, many functional and integrative medicine doctors prescribe nutrition-based protocols to treat patients with autoimmune disease.
Liu agreed that these kinds of treatments had potential, although more research is needed to understand how they affect the immune system.
“We know that gut microbiota are altered by stress, antibiotics, high-fat diet, and a ‘overly clean environment,’” Liu said. “It is reasonable to postulate that lifestyle interventions could help to prevent or treat autoimmune diseases.”