Gut Microbes Impact the Integrity of the Blood-Brain Barrier

Scientists have discovered that our natural gut microbes may just influence the blood-brain barrier, which protects the brain from harmful substances in the blood. The findings reveal that gut microbiota can impact brain development and function.

The blood-brain barrier is a highly selective barrier that prevents unwanted molecules and cells from entering the brain from the bloodstream. This means that it's important that this barrier remains intact.
Yet it seems that gut microbes, which can be influenced by diet, play a critical role in the integrity of this barrier.

The scientists compared the integrity and development of the blood-brain barrier between two groups of mice. The first group was raised in an environment where they were exposed to normal bacteria. The second group, called germ-free mice, was kept in a sterile environment without any bacteria.

"We showed that the presence of the maternal gut microbiota during late pregnancy blocked the passage of labeled antibodies from the circulation into the brain parenchyma of the growing fetus," said Viorica Braniste, first author of the new study, in a news release. "In contrast, in age-matched fetuses from germ-free mothers, these labeled antibodies easily crossed the blood-brain barrier and was detected within the brain parenchyma."

The findings reveal that alterations of our indigenous microbiota may have far-reaching consequences for the blood-brain barrier function throughout life.

"These findings further underscore the importance of maternal microbes during early life and that our bacteria are an integrated component of our body physiology," said Sven Pettersson, one of the researchers. "Given that the microbiome composition and diversity change over time, it is tempting to speculate that the blood-brain barrier integrity may also fluctuate depending on the biome."

The findings are published in the journal Science Translational Medicine.

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