Using the Human Microbiome to Treat Common Diseases

Using the Human Microbiome to Treat Common Diseases

Microbes living in us and on us outnumber our own cells. Microbiota in the human gut is one of the most densely populated bacterial ecosystems known in nature. It regulates metabolic function and immune responses and contributes to mood and behavior. Imbalances have been linked to different diseases including inflammatory bowel disease (IBD) and metabolic disorders. A healthy microbiome, on the other hand, can have a protective function as has been shown in the case of Helicobacter pylori, which was previously only known for its harmful effects.

Scientists now recognize that H.pylori – which incidentally, was also found in the stomach of 5,300-year-old Iceman Oetzi – can protect against acid reflux and asthma.

Microbiome or Microbiota?

Microbiome and microbiota have received a lot of press lately because of the scientific advances related to the treatment of gastrointestinal and immune diseases that involve microbial communities. There has been some ambiguity in the way the two terms are being used. Dr. Jonathan Eisen from the University of California, Davis noted that microbiome is now commonly used to refer to the collection of microorganisms that occupy a certain habitat in the body, for example, the human gut. Some other trusted sources, such as the scientific journal Nature, also define the microbiome as the genetic material within a microbiota. In their view, the microbiota refers to the entire collection of organisms. 

Although there appears to be some inconsistency in the use of terminology, the science community univocally agrees that the contribution of microbes to human health is significant.

Nonetheless, it can sometimes be challenging to study their direct influence and causal relationship to different diseases. 

Transferring the Microbiome between People

This month, a study was published in Nature Medicine that described the process of transferring the mother’s microbiome to her newborn child.

It has previously been established that babies born with cesarean section are more likely to develop autoimmune diseases. As their mode of delivery does not expose them to the vaginal microbiome, right after the birth, their gut microbiome resembles that of their mum’s skin. In contrast, vaginally born babies have a gut microbiome that resembles their mother’s vaginal microbiome, which appears to protect them against certain harmful conditions. An experiment designed by Maria Dominguez-Bello from New York University looked into transferring the mother’s vaginal microbiome to babies born by C-section. The mothers were swabbed and the babies were colonized immediately after birth. When tested after a month, newborns who were inoculated with the vaginal microbiome still had a microbiome that closely resembled their mother’s vagina. These transfers of vaginal flora following a C-section might become an important procedure in the future and could help prevent some auto-immune conditions.

Fecal transplantation or bacteriotherapy has also been explored. It has been applied to patients who have bacterial imbalance in their gut as a result of a previous antibiotic treatment that destroyed helpful bacteria.

People who have been diagnosed with recurrent C.deficile colitis can now be treated with a transfer of stool from a healthy donor.

Human-gut-on-a-chip Technology

A team from Harvard University made significant progress in studying gut bacteria and inflammation by using human-gut-on-a-chip technology to microengineer a controlled model of human intestines. This model — the size of a computer memory stick — mimics the natural conditions in the human intestines, which enables researchers to study bacterial overgrowth and inflammation of the gut. For the first time, scientists are able to analyze different pathophysiological responses and the contribution of individual pathogenes and cells in vitro.

Services like uBiome are also emerging, transforming the testing of human bacteria into citizen science. However, these popular institutions might have many limitations. The science is still in its infancy, and looking solely at the bacteria in our gut does not necessarily give us a comprehensive picture of the gut environment and overall intestinal health.

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