In a new mouse study, scientists at Weill Cornell Medicine discovered that a specific group of fungi found in the intestines can protect against intestinal injury and influence social behavior in mice. The findings add to a growing body of evidence that a “gut-immunity-brain axis” exists.
The study, “Mucosal fungi promote gut barrier function and social behavior via Type 17 immunity,” is published in the journal Cell, and showed a novel set of molecular signals connecting fungi in the gut to their host’s cells throughout the body, including immune cells and neurons.
The researchers added, “Fungal communities (the mycobiota) are an integral part of the gut microbiota, and their disruption contributes to local and gut-distal pathologies.” “However, the mechanisms by which intestinal fungi maintain homeostasis are unknown. The biogeography of the mycobiota along the gastrointestinal tract was studied, and a subset of fungi associated with the intestinal mucosa of mice and humans was discovered.”
“There was the fortification of those barrier functions when we added that specific fungal community to mice,”
The researchers also observed that mice carrying the fungal community in their gut displayed more social behavior than animals without these fungi.
The animals’ own T cells appear to be responsible for both effects. T cells were induced to secrete two immune signalling proteins, cytokines IL-22 and IL-17, by the fungi. Fungi-induced IL-22 strengthens the epithelium’s barrier function locally, whereas IL-17 enters the bloodstream and eventually reaches neurons with receptors.
Iliev explained, “There is this harmony—a kind of communication between or across different types of organisms.”
The researchers hope to dig deeper into that communication network. “We’re looking at the signals that are involved at the neuronal level in different brain regions,” said lead author Irina Leonardi, Ph.D., immunology in medicine instructor in Iliev’s lab at the Jill Roberts Institute for Research in IBD.
“This opens up a whole new area to investigate,” Iliev said.