Editors' ChoiceObesity

Shaping Up with the Gut Microbiota

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Science Translational Medicine  19 Nov 2014:
Vol. 6, Issue 263, pp. 263ec201
DOI: 10.1126/scitranslmed.aaa2064

Bacteria that take up residence within our bodies, our microbiota, have emerged as a powerful contributor to human health. Understanding how these bacterial communities are built and maintained will be important for future therapeutic applications. A long-standing question has been whether the composition of our microbiota is influenced only by environmental exposure or whether host genetics also shapes these bacterial communities. Ruth Ley and her colleagues finally provide an answer.

The authors obtained more than 1000 fecal samples from both dizygotic and monozygotic twins. Dizygotic twins are likely to have experienced similar environments but have a different genetic makeup. In contrast, monozygotic twins have experienced similar environments and also have identical genetics. The investigators also included about 100 fecal samples from unrelated individuals. Using sequencing techniques to analyze the complex community of microbes found within the stool samples of these individuals, the authors discovered that the newly identified bacterial family Christensenellaceae was one of the most highly “heritable” bacterial groups. This meant that in monozygotic twins the same organism, in similar abundance, was found in both twins of the twin pair, whereas there was no correlation between dizygotic twins or unrelated individuals. This shows that the genetics of an individual influences the type of resident microbes that reside in the body.

What does this mean for human health? The authors of the study correlated this bacterial family with body mass index (BMI) and found that the Christensenellaceae bacteria were enriched in the gut microbiota of lean individuals. They then transferred stool samples from lean individuals that were colonized with the Christensenellaceae bacteria or from obese individuals from the twins group into germ-free (gnotobiotic) mice and found that animals receiving microbes from obese individuals gained more weight than those given microbes from lean individuals. Last, the authors took human fecal samples that did not contain Christensenellaceae and spiked them with bacteria from this family and then colonized the guts of germ-free mice. Animals that received the Christensenellaceae microbiota did not gain as much weight as control animals, indicating the possibility that this family of bacteria can improve human health by preventing obesity. Although much remains to be done before these organisms can be used as the next weight loss aid, this study demonstrates that host genetics enables our microbial communities to “shape up” our health.

J. Goodrich et al., Human genetics shape the gut microbiome. Cell 159, 789–799 (2014). [Abstract]

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