Editors' ChoicePregnancy

Microbial Manipulation of Metabolism

See allHide authors and affiliations

Science Translational Medicine  22 Aug 2012:
Vol. 4, Issue 148, pp. 148ec153
DOI: 10.1126/scitranslmed.3004777

Humans coexist in commensality with a variety of microorganisms: there are roughly 100 trillion microorganisms in the intestine alone. Changes in gut microbiota composition are known to contribute to the development of metabolic disease by promoting inflammation, weight gain, and reduced insulin sensitivity. Now, Koren et al. show that host-microbial interactions during pregnancy are similar to those associated with metabolic syndrome.

To address how pregnancy affects the composition of gut microbiota, the authors characterized the microbial communities in stool samples from 91 pregnant women of varying body mass indices (BMIs) and gestational diabetes statuses. Bioinformatic analyses revealed a dramatic remodeling of the gut microbiota composition over the course of pregnancy. In the first trimester (T1), the gut microbiota was comparable with that of nonpregnant healthy control women. However, by the third trimester (T3) the authors noted an increase in bacterial diversity between pregnant women and a decrease in bacterial richness within each pregnant individual relative to T1 samples. The magnitude of these changes was unrelated to prepregnancy BMI, development of gestational diabetes, or previous number of births.

Some of the features of the T3-related microbial community reflected those of the inflammatory disease–associated microbiome. Because the later stages of pregnancy were characterized by a diabetogenic state (including hyperglycemia and reduced insulin sensitivity), the alterations in the gut microbiota might be related to these pregnancy-induced metabolic changes. To investigate the potential for pregnancy-associated microbiota to promote inflammation and alter host metabolism, the authors introduced human T1 or T3 microbiota into the guts of female germ-free mice. Transfer of T3 microbiota into the mouse model caused an increase in adiposity and a decrease in insulin sensitivity compared with T1, indicating that the T3 microbiota has the capacity to induce metabolic changes in the host that resemble those that occur in both pregnancy and the metabolic disease context.

Metabolic changes are necessary to support a healthy pregnancy, and this study suggests that gut microbiota play a role in this important transition. More surprising was the observation that gut microbiota in late pregnancy displays features that overlap with those associated with metabolic diseases in which altered host-microbial interactions influence host metabolism. This study provides another step toward the understanding of reproductive biology and its connection to obesity-related metabolic diseases.

O. Koren et al., Host remodeling of the gut microbiome and metabolic changes during pregnancy. Cell 150, 470–480 (2012). [Abstract]

Navigate This Article