Published November 22, 2017 | Cell Host Microbe

In recent years, research on the great protectors of gut health has focused near-exclusively on bacterial species, and not without reason. Bacteria have proven to be remarkably efficient at preventing tissue injury and augmenting systemic antimicrobial immunity.

Still, the overall map of the complicated roadways to gut health has been, at best, scientifically incomplete. Commensal enteric fungi were far lesser explored. That has changed.

In a study led by Sing Sing Way, MD, PhD, of the Division of Infectious Diseases, a team of researchers showed that commensal fungi can functionally replace intestinal bacteria in two important ways.

The fungi serve as a protective barrier to injury of mucosal tissues. They also calibrate a beneficial responsiveness in circulating immune cells.

They provide this safeguard for local and systemic immunity in an ingenuous way, by providing tonic microbial stimulation that does what good bacteria does.

That was a revelation.

“It was a big gap in knowledge,” Way says. “We were missing many other pieces of the puzzle, so what our paper shows is a broadening of the scope of what commensal microbes do.”

The microbes that colonize our skin and mucosal surfaces, such as lung, mouth and intestine, play a critical role in keeping us healthy.

But less was known about the unique biological properties that fuel that protective barrier.

“Our purpose,” Way says, “was to figure out if these protective benefits of bacteria are restricted. Or do fungi and viruses have these protective benefits as well? What we found is that, absolutely, these fungi do.”

That affirmation is now driving research into the potential use of fungi molecules as a clinical therapy, particularly for people who are taking antibiotics.