How a healthy microbiome reduces gut inflammation

The microbiome has a profound influence on our health, but it remains unclear exactly how our resident bacteria exert their power. A type of T cell appears to provide answers when it comes to gastrointestinal health, according to a study of the mouse microbiome.

The study, published in the journal Immunitydiscovered that when friendly, commensal microbes take up residence inside the gut, their host produces T cells that maintain gut health by neutralizing inflammation.

This discovery could lead to new treatments for inflammatory bowel disease (IBD).

“If we can replicate the way friendly microbes induce anti-inflammatory commensal T cells, we may be able to develop new treatments to prevent IBD-related intestinal inflammation,” says study leader Ivaylo Ivanov , Ph.D., associate professor of microbiology and immunology. at the Vagelos College of Physicians and Surgeons at Columbia University.

Multitasking T cells

Ivanov had previously discovered that the host produces specific T cells when friendly or commensal microbes take up residence inside the intestine. T cells work to keep microbes in check. “We wanted to know if these T cells had additional functions,” says Ivanov.

The study, conducted in tissue culture and in mice, determined that commensal T cells reduce inflammation by producing a cytokine called IL-10.

Commensal T cells are unusual because they perform opposing functions.

“Normally, tissues contain two types of T cells: one that promotes inflammation and clears infection and another that suppresses inflammation and helps turn off the immune response once the infection is cleared,” explains Ivanov. “We found that commensal induced T cells exhibit characteristics of both, likely because commensal microbes do not need to be eliminated and the immune response to them has evolved to be less inflammatory.”

The study also found that commensal T cells can suppress other types of T cells, suggesting that they represent a backup or additional system to prevent autoimmunity, which occurs when excessive inflammation triggers the immune system to attack the body’s own cells.

Potential role in obesity and diabetes

In addition to suggesting treatments for IBD, the study could also show how the gut microbiome influences the health of people suffering from obesity, diabetes or metabolic syndrome.

“We have already found that these T cells improved the health of mice with obesity and diabetes, and these improvements could be due to the anti-inflammatory activity of T cells that we describe here,” says Ivanov.

The laboratory is currently studying this possibility.