Hepatic gene expression co-regulated by diet-microbiota interactions (14 wk)

The enzymes that add and remove histone modifications are known to be exquisitely sensitive to endogenous small molecule metabolite availability. In this manner, chromatin can adapt to changes in environment, particularly diet-induced metabolic state. Importantly, gut microbiota contribute to robust host metabolic phenotypes, and produce a myriad of metabolites that are detectable in host circulation. Further, gut microbial community composition and metabolite production are regulated by host diet, as a major source of carbon and energy for the microbiota. While prior studies have reported robust host metabolic associations with gut microbiota, the mechanisms therein remain largely unknown. Here we demonstrate that microbial colonization regulates global histone acetylation and methylation in multiple host tissues including colon, adipose tissue, and liver. This regulatory relationship is altered by diet: a “Western-type” diet leads to a general suppression of the microbiota-dependent chromatin changes observed in a polysaccharide rich diet. Finally, we demonstrate that supplementation of germ-free mice with major products of gut bacterial fermentation (i.e., short-chain fatty acids acetate, propionate, and butyrate) is sufficient to recapitulate many of the effects of colonization on host epigenetic states. These findings have profound implications for understanding the complex functional interactions between diet, gut microbiota, and host health.