The Host Shapes the Gut Microbiota via Fecal MicroRNA.
Liu S, da Cunha AP, Rezende RM, Cialic R, Wei Z, Bry L, Comstock LE, Gandhi R, Weiner HL
Cell Host Microbe. Jan 2016. doi: 10.1016/j.chom.2015.12.005S1931-3128(15)00497-7
COMMENT: It is clear that the host shapes the microbiome. The authors describe that miRNAs are among the host factors influencing the microbiome. It has been described for mice and humans that miRNAs are abundant in fecal samples.
miRNAs are synthetized in the nucleus and processed in the cytoplasm where they do their function regulating expression. However it is becoming clear that they can reach the extracellular space and different body fluids. They have been also detected in human fecal samples.
The authors analyzed the presence of miRNAs in human and mouse fecal samples and found that there are miRNAs in a pattern similar to extracellular exosome RNAs. Those miRNAs were mainly produced by intestinal epithelial cells (IEC) and Hopx-positive cells.
Analyzing the microbiome composition they found a shift of the dominant bacterial phyla Firmicutes and Proteobacteria and at the family level, an increase of Bacteroidaceae and Helicobacteraceae and a decrease of Prevotellaceae, Porphyromonadaceae, Lachnospiraceae, and Ruminococcaceae.
It has been described that miRNAs can enter mitochondria and the authors demonstrate that miRNAs also enter bacteria and affect gene expression although this ability depends on each miRNA. Thus, host miRNAs can enter bacteria, such as Fusobacterium nucleatum and Escherichia coli, specifically regulate bacterial gene transcripts, and affect bacterial growth. Furthermore, administration of RNA and miRNA to mice with altered miRNA and microbiome restores some Microbiome changes.