Limitations and outlook
Dr. Clemente said in an interview that the researchers were “hopeful that the study would demonstrate a health benefit, as it does with some limitations.” The current study findings confirm some previous results showing that modification of the microbiomes of C-section infants is possible through a transfer of maternal vaginal microbes, he said.
“There is also an important aspect that was confirmed here: The lack of serious adverse events associated with the procedure, and the fact that transferring vaginal microbes did not increase the risk of adverse events compared to the control group or to vaginally-delivered infants. This is fundamental to establish that using rigorous exclusion criteria we can perform this procedure safely for infants and mothers,” he added.
“We are at very early stages yet to talk about clinical implications,” said Dr. Clemente. “This is one of the first studies to demonstrate a benefit to the transfer of microbes from mothers to infants, and as such it opens the way for future trials that confirm these findings. The clinical application is still in the future, but this is an important first step towards that goal.”
Interest in restoring gut microbiota to potentially benefit infants persists, but a recent study published in Frontiers and Cellular and Infection Microbiology contradicted the potential association between maternal vaginal microbiome and an infant’s gut microbiome based on an analysis of infant stool.
“There are many reasons why different studies might reach different conclusions: The experimental procedures, the analytical methods, the cohort under study,” Dr. Clemente said when asked to comment on the Frontiers study. “Further studies are needed to establish whether this procedure is equally effective under all conditions and whether health benefits are generalizable or specific to particular populations.”
Several research gaps remain, Dr. Clemente said. “First, neurodevelopment was measured through a questionnaire that captures various aspects such as communication, motor skills, or problem solving. While this is a standard way to establish that an infant is in the correct neurodevelopmental pathway, it is not a ‘hard’ measure of cellular or biochemical processes being impacted by the intervention. Some of our results suggest that there is a change in the metabolome of this infants, particularly an enrichment in GABA, a neurotransmitter, but the exact mechanisms by which the intervention is resulting in a health benefit still remains to be explored,” he said.
“We have an ongoing study here at Mount Sinai to test whether this microbial intervention can be effective in lowering the risk of developing food allergies in newborns who are at high risk, so that is another important future question: What other conditions could benefit from this approach,” said Dr. Clemente.
A third research goal, he added, is “determining what microbes precisely are responsible for the health benefits; this study uses a full microbial community to colonize infants. We show that this is effective and, importantly, that there were no significant adverse events in the treated infants,” he noted. “However, identifying what specific microbes are beneficial would further lower the risk of any potential side effects, while facilitating the development of drugs based on defined microbial consortia,” he said.