In our guts, and in the guts of all animals, resides a robust ecosystem of microbes known as the microbiome. Consisting of trillions of organisms — bacteria, fungi and viruses — the microbiome is essential for host health, providing important services ranging from nutrient processing to immune system development and maintenance.
Now, in a study comparing mice raised in a “germ free” environment and mice raised under more typical lab conditions, scientists have identified yet another key role of the microbes that live within us: mediator of host gene expression through the epigenome, the chemical information that regulates which genes in cells are active.
Writing online Nov. 23 in the journal Molecular Cell, a team of researchers from the University of Wisconsin–Madison describes new research helping tease out the mechanics of how the gut microbiome communicates with the cells of its host to switch genes on and off. The upshot of the study, another indictment of the so-called Western diet (high in saturated fats, sugar and red meat), reveals how the metabolites produced by the bacteria in the stomach chemically communicate with cells, including cells far beyond the colon, to dictate gene expression and health in its host.
“The bugs are somehow driving gene expression in the host through alteration of the epigenome,” explains John Denu, a UW–Madison professor of biomolecular chemistry and a senior researcher at the Wisconsin Institute for Discovery, and a co-author of the new study. “We’re starting to understand the mechanism of how and why diet and the microbiome matter.”
The study, which was led by Kimberly Krautkramer, an MD/Ph.D. student in the UW School of Medicine and Public Health, revealed key differences in gene regulation in conventionally raised mice and mice raised in a germ-free environment. The mice were provided with two distinct diets: one rich in plant carbohydrates similar to fruits and vegetables humans consume; the other mimicking a Western diet, high in simple sugars and fat.
To read more about this research, see the press release below.