Infants born to mothers with IBD have altered gut microbiome

Last Updated: 2019-05-22

By Will Boggs MD

NEW YORK (Reuters Health) - Infants of mothers with inflammatory bowel disease (IBD) have lower gut bacterial diversity and altered bacterial composition like their mothers, compared with control women and their infants, researchers report.

"This is the first study to demonstrate the potential effect of maternal IBD diagnosis on the microbiome colonization during early life," Dr. Inga Peter from Mount Sinai School of Medicine in New York City told Reuters Health by email. "More studies are needed to confirm our findings and investigate if this effect can be mitigated by positive environmental exposures (e.g., vaginal delivery, breastfeeding, no antibiotic use, etc.)."

Family history is the strongest risk factor for developing IBD, but the genetic loci identified so far do not fully explain its heritability. Some studies have suggested that mothers may be more likely than fathers to transmit IBD, but it has been unclear whether the maternal microbiome composition during pregnancy is altered in IBD and how it might affect the offspring.

Dr. Peter's team examined the diversity and taxonomy of the microbiome of 40 pregnant women with and 81 without IBD and their babies, 26 of whom were born to women with IBD. Then they assessed the effects of IBD-associated maternal and infant microbiota on germ-free mice.

Throughout pregnancy, women with IBD had lower gut alpha-diversity than controls. Control women showed a continuous decrease in global alpha-diversity from the first to the third trimester, whereas women with IBD showed a nonsignificant trend towards a slight increase.

Biomarker analysis showed that the major differences between mothers with and without IBD were driven by an enrichment of the Gammaproteobacteria class and a depletion of the Bacteroidetes phylum in mothers with IBD, the researchers report in Gut, online April 29.

The gut microbiome of infants born to mothers with IBD showed lower diversity and variation in overall abundance, with enrichment of the same microbial groups as their mothers, compared with babies born to control others, as early as seven days and as late as 90 days after birth.

Maternal IBD diagnosis was a significant predictor of the baby's microbiome diversity regardless of the mode of delivery (i.e., vaginally or via C-section).

Germ-free mice inoculated with stool from third-trimester IBD mothers or from 90-day infants of IBD mothers showed significantly reduced microbial diversity and fewer class-switched memory B cells and regulatory T cells in the colon, compared with those inoculated with non-IBD mother/baby stools.

"The fact that the microbiome of babies reflects maternal IBD diagnosis and that mice who receive the microbiome from babies born to mothers with IBD develop a suboptimal immune system was the most surprising," Dr. Peter said. "This finding implies some kind of bacterial transmission in utero that may have an effect on the priming of the immune system with potential long-term health consequences."

"The potential implication would be to try to modify the maternal gut microbiome when it matters the most for the baby, which could be during the 3rd trimester of pregnancy or even earlier," she said. "We are conducting an intervention trial now aimed at providing a dietary intervention versus habitual diet to pregnant women with and without Crohn's disease and see if it may foster a healthier microbiome during early life, the critical time window of the development of the immune system."

"Also," Dr. Peter said, "these findings can apply to other immune-mediated diseases during pregnancy."

SOURCE: https://bit.ly/2QlkWS0

Gut 2019.